[Tutor] While loop homework: was Re: Tutor Digest, Vol 161, Issue 33
On 30/07/17 23:36, Borisco Bizaro wrote:
> a=1
> b=2
> while a input ("enter another price :")
Do 'a' or 'b' ever change?
Does 'a print"\n\n press 0 key to stop"
Does the user ever get the chance to enter a value?
If they were, Where is the value stored and is the
value ever used?
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of Tutor digest..."
Please follow the instructions as requested.
It helps find answers in the archives.
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
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Re: [Tutor] While Loop Question
2017-05-11 3:53 GMT+02:00 Rafael Skovron : > Sorry I left out the indents in my previous email. It seems like j is > always reset to zero. Why does j vary? > > Are there two different instances of j going on? > > > for i in range(1, 5): > > j=0 > >while j < i: > > print(j, end = " ") > > j += 1 > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > Hi, As there is a j = 0 statement in the for cycle, it will be set to 0 every time the while cycle finishes. (The while cycle will then increment j, then if j == i j will be set to 0 again). George ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While Loop Question
On Wed, May 10, 2017 at 06:53:21PM -0700, Rafael Skovron wrote: > Sorry I left out the indents in my previous email. It seems like j is > always reset to zero. Why does j vary? Because you run code that adds 1 to j. > Are there two different instances of j going on? No. Try to run the code in your head and see what happens. See below: > for i in range(1, 5): > j=0 > while j < i: > print(j, end = " ") > j += 1 We start by setting i = 1, then the body of the for-loop begins. That sets j = 0, and since 0 < 1, we enter the while-loop. Inside the while-loop, we print j (0), then add 1 to j which makes it 1. Then we return to the top of the while-loop. Since 1 is NOT less than 1, we exit the while-loop and return to the top of the for-loop. Now we set i = 2, and continue into the body of the for-loop. That sets j = 0 (again!) and since 0 < 2, we enter the while-loop. Inside the while-loop, we print j (0), then add 1 to j which makes it 1. Then we return to the top of the while-loop. Since 1 < 2, we continue inside the body, print j (1), then add 1 to j which makes it 2. Since 2 is not LESS than 2, we exit the while-loop and return to the top of the for-loop. Now we set i = 3, and continue into the body of the for-loop. That sets j = 0 (again!) and since 0 < 3, we enter the while-loop. Inside the while-loop, we follow the same steps and print 0, then 1, then 2, then exit the while-loop and return to the top of the for-loop. Now we set i = 4, and again continue into the while-loop to print 0, 1, 2 and finally 3, then exit the while-loop and return to the top of the for-loop, which is now complete. -- Steve ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] While Loop Question
Sorry I left out the indents in my previous email. It seems like j is always reset to zero. Why does j vary? Are there two different instances of j going on? for i in range(1, 5): j=0 while j < i: print(j, end = " ") j += 1 ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While Loop Help
While Alan has given you a far better solution, I feel someone should
mention the break statement as you will likely come across it a lot, and it
is quite an important flow control statement.
You could add a break statement to the else which would break out of the
while loop.
https://docs.python.org/3.4/reference/simple_stmts.html#break
Refactored to include a break
--
...
the_number = random.randint(1, 100)
win = false
tries = 0
guess = int(input("Take a guess: "))
while tries < 10:
guess = int(input("Take a guess: "))
tries += 1
if guess > the_number:
print("Lower...")
elif guess < the_number:
print("Higher...")
else:
win = true
break
if win:
print("You win")
else:
print("You fail! The number was {0}".format(the_number))
input("\n\nPress the enter key to exit.")
--
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Re: [Tutor] While Loop Help
On Wed, Dec 10, 2014 at 11:20:12PM -0500, Matthew Nappi wrote:
> I am working on the challenges from “Python Programming for the Absolute
> Beginner” Chapter 3. I am asked to modify the original code pasted below
> to limit the number of guesses a player has to guess the number. I did so
> (code pasted below); however if a player guesses the right number they
> still receive an ending message indicating that they failed. How can I
> modify the code without using any advanced techniques to have a different
> message in the event of a successful guess? Thanks in advance!
[...]
> *My Modified Code:*
> import random
> print("\tWelcome to 'Guess My Number'!")
> print("\nI'm thinking of a number between 1 and 100.")
> print("Try to guess it in as few attempts as possible.\n")
>
> # set the initial values
> the_number = random.randint(1, 100)
> guess = int(input("Take a guess: "))
> tries = 1
>
> # guessing loop
> while guess != the_number and tries < 10:
> if guess > the_number:
> print("Lower...")
> elif guess < the_number:
> print("Higher...")
> else:
> print("You win.")
> guess = int(input("Take a guess: "))
> tries += 1
Follow the code: start at the top of the while loop. The next thing that
happens is that the computer checks whether guess > the number,
otherwise whether guess < the number, otherwise they must be equal.
Whichever one happens, a message is printed. What happens next?
The next line executes, which says "take a guess". That isn't right,
since that forces the player to guess even after they've won.
There are a few ways to deal with that. One way would be to change the
while loop to something like this:
the_number = random.randint(1, 100)
guess = -99 # Guaranteed to not equal the_number.
tries = 0 # Haven't guessed yet.
while guess != the_number and and tries < 10:
tries += 1
guess = int(input("Take a guess: "))
if guess < the_number:
print("too low")
elif guess > the_number:
print("too high")
else:
print("you win!")
Notice how this differs from the earlier version? Instead of asking the
player to guess at the *end* of the loop, after checking whether the
guess was right, you ask the player to guess at the *start* of the loop.
That means you don't need an extra guess at the beginning, and it means
you don't get an extra, unneeded guess even after you win.
Now let's move on to the next line:
> print("You fail! The number was", the_number)
This line *always prints*, regardless of whether you have won or not.
The easiest way to fix that is to just check whether or not the player
guessed correctly:
if guess != the_number:
print("You fail! The number was", the_number)
--
Steven
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Re: [Tutor] While Loop Help
On 11/12/14 04:20, Matthew Nappi wrote:
(code pasted below); however if a player guesses the right number they
still receive an ending message indicating that they failed. How can I
modify the code without using any advanced techniques to have a different
message in the event of a successful guess? Thanks in advance!
import random
print("\tWelcome to 'Guess My Number'!")
print("\nI'm thinking of a number between 1 and 100.")
print("Try to guess it in as few attempts as possible.\n")
the_number = random.randint(1, 100)
guess = int(input("Take a guess: "))
tries = 1
while guess != the_number and tries < 10:
if guess > the_number:
print("Lower...")
elif guess < the_number:
print("Higher...")
else:
print("You win.")
guess = int(input("Take a guess: "))
tries += 1
So far so good, except that you probably don;t want
the winner to have to input another number after
being told he already won.
You can avoid that by making the initial value for
guess be something invalid, then move the input
line to the top of the while loop:
guess = 0
while guess != the_number and tries < 10:
guess = int(input("Take a guess: "))
tries += 1
... the if/else code here.
print("You fail! The number was", the_number)
But you always print this regardless of the result.
You need to put a test around it to check whether
the guess equals the number and only print this
if it is not.
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos
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[Tutor] While Loop Help
Hello All:
I am working on the challenges from “Python Programming for the Absolute
Beginner” Chapter 3. I am asked to modify the original code pasted below
to limit the number of guesses a player has to guess the number. I did so
(code pasted below); however if a player guesses the right number they
still receive an ending message indicating that they failed. How can I
modify the code without using any advanced techniques to have a different
message in the event of a successful guess? Thanks in advance!
*Original Code:*
# Guess My Number
#
# The computer picks a random number between 1 and 100
# The player tries to guess it and the computer lets
# the player know if the guess is too high, too low
# or right on the money
import random
print("\tWelcome to 'Guess My Number'!")
print("\nI'm thinking of a number between 1 and 100.")
print("Try to guess it in as few attempts as possible.\n")
# set the initial values
the_number = random.randint(1, 100)
guess = int(input("Take a guess: "))
tries = 1
# guessing loop
while guess != the_number:
if guess > the_number:
print("Lower...")
else:
print("Higher...")
guess = int(input("Take a guess: "))
tries += 1
print("You guessed it! The number was", the_number)
print("And it only took you", tries, "tries!\n")
input("\n\nPress the enter key to exit.")
*My Modified Code:*
# Guess My Number
#
# The computer picks a random number between 1 and 100
# The player tries to guess it and the computer lets
# the player know if the guess is too high, too low
# or right on the money
import random
print("\tWelcome to 'Guess My Number'!")
print("\nI'm thinking of a number between 1 and 100.")
print("Try to guess it in as few attempts as possible.\n")
# set the initial values
the_number = random.randint(1, 100)
guess = int(input("Take a guess: "))
tries = 1
# guessing loop
while guess != the_number and tries < 10:
if guess > the_number:
print("Lower...")
elif guess < the_number:
print("Higher...")
else:
print("You win.")
guess = int(input("Take a guess: "))
tries += 1
print("You fail! The number was", the_number)
input("\n\nPress the enter key to exit.")
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Re: [Tutor] While Loop and Threads
this construct: On Tue, Jul 15, 2014 at 5:09 AM, Oğuzhan Öğreden wrote: > > > while time_now < time_finish: # counter and count_until defined > somewhere above and > if g_threadStop.is_set() == False: > # return something or raise an exception to signal > iteration was interrupted > > might work better as something like while (time_now < time_finish) and (not g_threadStop.is_set()): to avoid the 'interrupt iteration' dilemma ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While Loop and Threads
Apologies, I didn't answer your question.
while time_now < time_finish: # counter and count_until defined
somewhere above and
if g_threadStop.is_set() == False:
# return something
Thread methods are typically void, meaning they return nothing. At least
this is the case in other languages, so I would expect the return to fail.
Also, what would you be returning it to?
Perhaps just a return without a value to indicate exit. (Probably some
reading required here)
Exceptions should be raised when something occurs that you were not
expecting and not used as an exit mechanism for normal operation.
Where to place the timer is up to you. Another thread is an option, but is
it necessary? Overhead needs to be considered.
--
James
On 15 July 2014 14:14, James Chapman wrote:
> So if I understand this correctly, you want to start a thread and then
> stop it after a certain time period?
>
> Here's an adapted example that includes a timer. (I believe in learning by
> example where possible)
> With that said, if it were my code going into production I'd move the
> timer logic out of the thread and only signal the thread when it should
> exit. Keep the logic within the thread simple and try and make each
> method/function do one thing only. It makes for testable, reusable code.
>
> In my new example
> * The first thread should exit because the time limit is met.
> * The second thread should exit because the Event is set.
>
> Hope this helps...
>
> James
>
>
>
> import time
> import threading
>
> class ThreadExample(object):
>
> def __init__(self):
> self.thread1Stop = threading.Event()
> self.thread2Stop = threading.Event()
> self.timeFinish = time.time() + 12
>
> def threadWorkerOne(self, _arg1, _arg2):
> print("THREAD1 - started with args: %s, %s" % (_arg1, _arg2))
> while(not self.thread1Stop.is_set()):
> while(time.time() < self.timeFinish):
> print("THREAD1 - Running")
> if (self.thread1Stop.is_set()):
> break # Break out of the time while loop
> time.sleep(1)
> if time.time() > self.timeFinish:
> print("THREAD1 - Time limit exceeded")
> self.thread1Stop.set()
> print("THREAD1 - Exiting because thread1Stop is TRUE")
>
> def threadWorkerTwo(self, _arg1, _arg2):
> print("THREAD2 - started with args: %s, %s" % (_arg1, _arg2))
> while(not self.thread2Stop.is_set()):
> while(time.time() < self.timeFinish):
> print("THREAD2 - Running")
> if (self.thread2Stop.is_set()):
> break # Break out of the time while loop
> time.sleep(1)
> if time.time() > self.timeFinish:
> print("THREAD2 - Time limit exceeded")
> self.thread2Stop.set()
> print("THREAD2 - Exiting because thread2Stop is TRUE")
>
> def main(self):
> t1 = threading.Thread(target=self.threadWorkerOne, args = ("arg1",
> "arg2"))
> t1.start()
> t2 = threading.Thread(target=self.threadWorkerTwo, args = ("arg1",
> "arg2"))
> t2.start()
> print("MAIN - sleep(5)")
> time.sleep(5)
> print("MAIN - setting thread1Stop")
> self.thread1Stop.set()
> print("MAIN - sleep(10)")
> time.sleep(10)
> print("MAIN - exiting...")
>
> if __name__ == '__main__':
> runExample = ThreadExample()
> runExample.main()
>
>
>
>
>
>
>
> --
> James
>
>
> On 15 July 2014 11:09, Oğuzhan Öğreden wrote:
>
>> Thanks!
>>
>> I'll have a side question. If I implement this idea to my case,
>> threadWorker() would look like this:
>>
>>
>> def threadWorker(_arg1, _arg2):
>> print("Starting worker thread with args: %s, %s" % (_arg1, _arg2))
>> while g_threadStop.is_set() == False:
>> ## here comes a for loop:
>> while time_now < time_finish: # time_finish and counter
>> defined somewhere above and
>> print("Thread running.") # and expression of the
>> condition is intentionally (and necessarily, I believe)
>> counter += 1 # left out of for
>> expression.
>> print(counter)
>> time.sleep(1)
>> print("Thread exiting...")
>>
>> Of course in this case value of g_threadStop.is_set() is not checked
>> until for loop finishes its iteration. Would the suggestion below be a good
>> way to handle the event signal?
>>
>>
>> def threadWorker(_arg1, _arg2):
>> print("Starting worker thread with args: %s, %s" % (_arg1, _arg2))
>> ## here comes a for loop:
>> while time_now < time_finish: # counter and count_until defined
>> somewhere above and
>> if g_threadStop.is_set() == False:
>> # return something or raise an exception to signal
>> iteration was interrupted
>> print("Thread running.
Re: [Tutor] While Loop and Threads
So if I understand this correctly, you want to start a thread and then stop
it after a certain time period?
Here's an adapted example that includes a timer. (I believe in learning by
example where possible)
With that said, if it were my code going into production I'd move the timer
logic out of the thread and only signal the thread when it should exit.
Keep the logic within the thread simple and try and make each
method/function do one thing only. It makes for testable, reusable code.
In my new example
* The first thread should exit because the time limit is met.
* The second thread should exit because the Event is set.
Hope this helps...
James
import time
import threading
class ThreadExample(object):
def __init__(self):
self.thread1Stop = threading.Event()
self.thread2Stop = threading.Event()
self.timeFinish = time.time() + 12
def threadWorkerOne(self, _arg1, _arg2):
print("THREAD1 - started with args: %s, %s" % (_arg1, _arg2))
while(not self.thread1Stop.is_set()):
while(time.time() < self.timeFinish):
print("THREAD1 - Running")
if (self.thread1Stop.is_set()):
break # Break out of the time while loop
time.sleep(1)
if time.time() > self.timeFinish:
print("THREAD1 - Time limit exceeded")
self.thread1Stop.set()
print("THREAD1 - Exiting because thread1Stop is TRUE")
def threadWorkerTwo(self, _arg1, _arg2):
print("THREAD2 - started with args: %s, %s" % (_arg1, _arg2))
while(not self.thread2Stop.is_set()):
while(time.time() < self.timeFinish):
print("THREAD2 - Running")
if (self.thread2Stop.is_set()):
break # Break out of the time while loop
time.sleep(1)
if time.time() > self.timeFinish:
print("THREAD2 - Time limit exceeded")
self.thread2Stop.set()
print("THREAD2 - Exiting because thread2Stop is TRUE")
def main(self):
t1 = threading.Thread(target=self.threadWorkerOne, args = ("arg1",
"arg2"))
t1.start()
t2 = threading.Thread(target=self.threadWorkerTwo, args = ("arg1",
"arg2"))
t2.start()
print("MAIN - sleep(5)")
time.sleep(5)
print("MAIN - setting thread1Stop")
self.thread1Stop.set()
print("MAIN - sleep(10)")
time.sleep(10)
print("MAIN - exiting...")
if __name__ == '__main__':
runExample = ThreadExample()
runExample.main()
--
James
On 15 July 2014 11:09, Oğuzhan Öğreden wrote:
> Thanks!
>
> I'll have a side question. If I implement this idea to my case,
> threadWorker() would look like this:
>
>
> def threadWorker(_arg1, _arg2):
> print("Starting worker thread with args: %s, %s" % (_arg1, _arg2))
> while g_threadStop.is_set() == False:
> ## here comes a for loop:
> while time_now < time_finish: # time_finish and counter
> defined somewhere above and
> print("Thread running.") # and expression of the
> condition is intentionally (and necessarily, I believe)
> counter += 1 # left out of for
> expression.
> print(counter)
> time.sleep(1)
> print("Thread exiting...")
>
> Of course in this case value of g_threadStop.is_set() is not checked until
> for loop finishes its iteration. Would the suggestion below be a good way
> to handle the event signal?
>
>
> def threadWorker(_arg1, _arg2):
> print("Starting worker thread with args: %s, %s" % (_arg1, _arg2))
> ## here comes a for loop:
> while time_now < time_finish: # counter and count_until defined
> somewhere above and
> if g_threadStop.is_set() == False:
> # return something or raise an exception to signal
> iteration was interrupted
> print("Thread running.") # and expression of the condition
> is intentionally (and necessarily, I believe)
> counter += 1 # left out of for expression.
> time.sleep(1)
> print("Iteration done.")
>
> This comes with a problem, due to time.sleep(1), signal is handled with a
> delay. I can think of a work around through GTK:
>
>1. changing (1) to something like while time_now < time_finish -
>actually that is the way it is in original code.
>2. dealing with the counter in the GTK main loop since it's main use
>is for GTK display of the timer.
>
> But let's now follow your advice and leave GTK out for a while and keep
> imagining I want:
>
>1. Command line output for the timer.
>2. Event signal handling without a delay.
>
> I have a felling that 'thread-way of thinking' would come up with another
> thread for counter. Is that correct? If yes, would there be an obvious
> advantage to either using GTK main loop or dealing with another thread?
>
>
Re: [Tutor] While Loop and Threads
Thanks!
I'll have a side question. If I implement this idea to my case,
threadWorker() would look like this:
def threadWorker(_arg1, _arg2):
print("Starting worker thread with args: %s, %s" % (_arg1, _arg2))
while g_threadStop.is_set() == False:
## here comes a for loop:
while time_now < time_finish: # time_finish and counter defined
somewhere above and
print("Thread running.") # and expression of the
condition is intentionally (and necessarily, I believe)
counter += 1 # left out of for
expression.
print(counter)
time.sleep(1)
print("Thread exiting...")
Of course in this case value of g_threadStop.is_set() is not checked until
for loop finishes its iteration. Would the suggestion below be a good way
to handle the event signal?
def threadWorker(_arg1, _arg2):
print("Starting worker thread with args: %s, %s" % (_arg1, _arg2))
## here comes a for loop:
while time_now < time_finish: # counter and count_until defined
somewhere above and
if g_threadStop.is_set() == False:
# return something or raise an exception to signal
iteration was interrupted
print("Thread running.") # and expression of the condition is
intentionally (and necessarily, I believe)
counter += 1 # left out of for expression.
time.sleep(1)
print("Iteration done.")
This comes with a problem, due to time.sleep(1), signal is handled with a
delay. I can think of a work around through GTK:
1. changing (1) to something like while time_now < time_finish -
actually that is the way it is in original code.
2. dealing with the counter in the GTK main loop since it's main use is
for GTK display of the timer.
But let's now follow your advice and leave GTK out for a while and keep
imagining I want:
1. Command line output for the timer.
2. Event signal handling without a delay.
I have a felling that 'thread-way of thinking' would come up with another
thread for counter. Is that correct? If yes, would there be an obvious
advantage to either using GTK main loop or dealing with another thread?
2014-07-14 20:24 GMT+02:00 James Chapman :
> OK, so I mocked up an example now...
>
>
>
> import time
> import threading
>
> g_threadStop = threading.Event()
>
> def threadWorker(_arg1, _arg2):
> print("Starting worker thread with args: %s, %s" % (_arg1, _arg2))
> while(not g_threadStop.is_set()):
> print("Thread running.")
> time.sleep(1)
> print("Thread exiting...")
>
> def main():
> t = threading.Thread(target=threadWorker, args = ("arg1", "arg2"))
> t.start()
> print("Main thread sleeping for 10 seconds...")
> time.sleep(5)
> print("Main thread setting g_threadStop")
> g_threadStop.set()
> time.sleep(3)
> print("Main thread exiting...")
>
> if __name__ == '__main__':
> main()
>
>
>
>
>
> --
> James
>
>
> On 14 July 2014 19:03, James Chapman wrote:
>
>> Multi-threading takes practice!
>>
>> Are you using an event object to signal the thread should exit? I'm
>> guessing you're just using a bool which is why it does not work.
>>
>> See: https://docs.python.org/3.4/library/threading.html#event-objects
>>
>> I'm very short on time and the moment and therefore can't mock up a
>> working example. If I have time later/tomorrow and you haven't solved it or
>> no one else has commented I'll try and put something together.
>>
>> IMO, move away from GTK until you get threading working as expected, then
>> add the additional layer. Solve one problem at a time.
>>
>> James
>>
>> --
>> James
>>
>>
>> On 13 July 2014 12:23, Oğuzhan Öğreden wrote:
>>
>>> Hi,
>>>
>>> I've been practicing with multithreading and gtk for a while and
>>> recently have observed something I can't quite grasp.
>>>
>>> This is basically a timer with a settings window and a countdown window
>>> which is produced after setting_window passes necessary arguments to thread.
>>>
>>> I have a while loop which counts time, inside the thread, while variable
>>> "runner" is True, which looks like this:
>>>
>>> def run(self):
>>> cycle = ['work', 'break', 'long_break']
>>> cycle = cycle[:2]*self.workn+cycle[3]
>>> self.runner = True
>>> sec_count = timedelta(seconds=1)
>>>
>>> while self.runner == True:
>>> for i in cycle:
>>> self.setState(i)
>>> print('Start:', i, datetime.now())
>>>
>>> while self.end_time > datetime.now():
>>> time.sleep(1)
>>> self.duration -= sec_count
>>>
>>> self.count[self.state] += 1
>>>
>>> And I want countdown to stop when countdown_window receives delete
>>> event, thus I have a countdown_window.stop() function which is defined as
>>> follows:
>>>
>>> def stop(self, *args):
>>> pom.count[pom.state] -= 1
>>>
Re: [Tutor] While Loop and Threads
OK, so I mocked up an example now...
import time
import threading
g_threadStop = threading.Event()
def threadWorker(_arg1, _arg2):
print("Starting worker thread with args: %s, %s" % (_arg1, _arg2))
while(not g_threadStop.is_set()):
print("Thread running.")
time.sleep(1)
print("Thread exiting...")
def main():
t = threading.Thread(target=threadWorker, args = ("arg1", "arg2"))
t.start()
print("Main thread sleeping for 10 seconds...")
time.sleep(5)
print("Main thread setting g_threadStop")
g_threadStop.set()
time.sleep(3)
print("Main thread exiting...")
if __name__ == '__main__':
main()
--
James
On 14 July 2014 19:03, James Chapman wrote:
> Multi-threading takes practice!
>
> Are you using an event object to signal the thread should exit? I'm
> guessing you're just using a bool which is why it does not work.
>
> See: https://docs.python.org/3.4/library/threading.html#event-objects
>
> I'm very short on time and the moment and therefore can't mock up a
> working example. If I have time later/tomorrow and you haven't solved it or
> no one else has commented I'll try and put something together.
>
> IMO, move away from GTK until you get threading working as expected, then
> add the additional layer. Solve one problem at a time.
>
> James
>
> --
> James
>
>
> On 13 July 2014 12:23, Oğuzhan Öğreden wrote:
>
>> Hi,
>>
>> I've been practicing with multithreading and gtk for a while and recently
>> have observed something I can't quite grasp.
>>
>> This is basically a timer with a settings window and a countdown window
>> which is produced after setting_window passes necessary arguments to thread.
>>
>> I have a while loop which counts time, inside the thread, while variable
>> "runner" is True, which looks like this:
>>
>> def run(self):
>> cycle = ['work', 'break', 'long_break']
>> cycle = cycle[:2]*self.workn+cycle[3]
>> self.runner = True
>> sec_count = timedelta(seconds=1)
>>
>> while self.runner == True:
>> for i in cycle:
>> self.setState(i)
>> print('Start:', i, datetime.now())
>>
>> while self.end_time > datetime.now():
>> time.sleep(1)
>> self.duration -= sec_count
>>
>> self.count[self.state] += 1
>>
>> And I want countdown to stop when countdown_window receives delete event,
>> thus I have a countdown_window.stop() function which is defined as follows:
>>
>> def stop(self, *args):
>> pom.count[pom.state] -= 1
>> pom.runner = False # refers to the runner of the thread.
>> print(pom.runner) # prints False,
>> Gtk.main_quit()
>>
>> What I expect to happen is that while loop to break, but it does not.
>>
>> Any suggestions?
>>
>> Best,
>> Oğuzhan
>>
>> ___
>> Tutor maillist - Tutor@python.org
>> To unsubscribe or change subscription options:
>> https://mail.python.org/mailman/listinfo/tutor
>>
>>
>
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Re: [Tutor] While Loop and Threads
Multi-threading takes practice!
Are you using an event object to signal the thread should exit? I'm
guessing you're just using a bool which is why it does not work.
See: https://docs.python.org/3.4/library/threading.html#event-objects
I'm very short on time and the moment and therefore can't mock up a working
example. If I have time later/tomorrow and you haven't solved it or no one
else has commented I'll try and put something together.
IMO, move away from GTK until you get threading working as expected, then
add the additional layer. Solve one problem at a time.
James
--
James
On 13 July 2014 12:23, Oğuzhan Öğreden wrote:
> Hi,
>
> I've been practicing with multithreading and gtk for a while and recently
> have observed something I can't quite grasp.
>
> This is basically a timer with a settings window and a countdown window
> which is produced after setting_window passes necessary arguments to thread.
>
> I have a while loop which counts time, inside the thread, while variable
> "runner" is True, which looks like this:
>
> def run(self):
> cycle = ['work', 'break', 'long_break']
> cycle = cycle[:2]*self.workn+cycle[3]
> self.runner = True
> sec_count = timedelta(seconds=1)
>
> while self.runner == True:
> for i in cycle:
> self.setState(i)
> print('Start:', i, datetime.now())
>
> while self.end_time > datetime.now():
> time.sleep(1)
> self.duration -= sec_count
>
> self.count[self.state] += 1
>
> And I want countdown to stop when countdown_window receives delete event,
> thus I have a countdown_window.stop() function which is defined as follows:
>
> def stop(self, *args):
> pom.count[pom.state] -= 1
> pom.runner = False # refers to the runner of the thread.
> print(pom.runner) # prints False,
> Gtk.main_quit()
>
> What I expect to happen is that while loop to break, but it does not.
>
> Any suggestions?
>
> Best,
> Oğuzhan
>
> ___
> Tutor maillist - Tutor@python.org
> To unsubscribe or change subscription options:
> https://mail.python.org/mailman/listinfo/tutor
>
>
___
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[Tutor] While Loop and Threads
Hi,
I've been practicing with multithreading and gtk for a while and recently
have observed something I can't quite grasp.
This is basically a timer with a settings window and a countdown window
which is produced after setting_window passes necessary arguments to thread.
I have a while loop which counts time, inside the thread, while variable
"runner" is True, which looks like this:
def run(self):
cycle = ['work', 'break', 'long_break']
cycle = cycle[:2]*self.workn+cycle[3]
self.runner = True
sec_count = timedelta(seconds=1)
while self.runner == True:
for i in cycle:
self.setState(i)
print('Start:', i, datetime.now())
while self.end_time > datetime.now():
time.sleep(1)
self.duration -= sec_count
self.count[self.state] += 1
And I want countdown to stop when countdown_window receives delete event,
thus I have a countdown_window.stop() function which is defined as follows:
def stop(self, *args):
pom.count[pom.state] -= 1
pom.runner = False # refers to the runner of the thread.
print(pom.runner) # prints False,
Gtk.main_quit()
What I expect to happen is that while loop to break, but it does not.
Any suggestions?
Best,
Oğuzhan
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Re: [Tutor] While loop issue, variable not equal to var or var
On Sat, Jul 12, 2014 at 02:39:12PM +0200, Wolfgang Maier wrote: [...] > Very interesting advice. Wasn't aware at all of this feature of casefold. > As a native German speaker, I have to say that your last two examples > involving the capital ß are pretty contrived: although the capital ß is > part of unicode, it is not an official part of the German alphabet and > nobody is using it (in fact, I had to look it up in Wikipedia now to > learn what that letter is). Interestingly, although capital ß is not official, it used to be a lot more common than it is now, and never quite disappeared: http://opentype.info/blog/2011/01/24/capital-sharp-s/ Now that the common fonts provided on Windows support the capital sharp s, I wouldn't be surprised if it starts to come back into vogue. Typesetters will be at the forefront, since they care about the look of things: http://www.glyphsapp.com/tutorials/localize-your-font-german-capital-sharp-s > An even better example than the rest of yours would be Kuß (German for > the noun kiss), which only people above 30 (like me) still spell this > way, but younger people spell Kuss since the official rules have changed > over the last 10 years. > In this particular case, you should definitely be prepared to handle > "Kuss" and "Kuß" as legal input. Good example! Thank you! -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
On 12/07/14 13:19, Steven D'Aprano wrote: Because the person might have typed any of: grosse große etc., and you want to accept them all, just like in English The bit I was missing was that a German user might use the ss version instead the ß so testing for either of them alone is insufficient. lower() or casefold() would deal with the mixed case variations, but lower() would not fix the ss v ß issues. Thanks, -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
On 12.07.2014 14:20, Dave Angel wrote: I don't remember my high school German enough to remember if the ß character is an example, but in various languages there are characters that exist only in uppercase, and whose lowercase equivalent is multiple letters. Or vice versa. And characters that have multiple valid spellings in uppercase, but only one in lowercase. If the latter is true for German, perhaps GROSSE and GROßE are valid uppercase, but only grosse for lowercase. No, that's not the case. Only große is valid lowercase, but many people got so used to computers not dealing with ß correctly that they'd type grosse automatically. Conversely, since there is no official capital form of ß (see my reply to Steven), GROSSE is standard uppercase although you might encounter GROßE occasionally. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
On 12.07.2014 14:19, Steven D'Aprano wrote: On Sat, Jul 12, 2014 at 11:27:17AM +0100, Alan Gauld wrote: On 12/07/14 10:28, Steven D'Aprano wrote: If you're using Python 3.3 or higher, it is better to use message.casefold rather than lower. For English, there's no real difference: ... but it can make a difference for non-English languages: py> "Große".lower() # German for "great" or "large" 'große' py> "Große".casefold() 'grosse' You learn something new etc... But I'm trying to figure out what difference this makes in practice? If you were targeting a German audience wouldn't you just test against the German alphabet? After all you still have to expect 'grosse' which isn't English, so if you know to expect grosse why not just test against große instead? Because the person might have typed any of: grosse GROSSE gROSSE große Große GROßE GROẞE etc., and you want to accept them all, just like in English you'd want to accept any of GREAT great gREAT Great gReAt etc. Hence you want to fold everything to a single, known, canonical version. Case-fold will do that, while lowercasing won't. (The last example includes a character which might not be visible to many people, since it is quite unusual and not supported by many fonts yet. If it looks like a box or empty space for you, it is supposed to be capital sharp-s, matching the small sharp-s ß.) Very interesting advice. Wasn't aware at all of this feature of casefold. As a native German speaker, I have to say that your last two examples involving the capital ß are pretty contrived: although the capital ß is part of unicode, it is not an official part of the German alphabet and nobody is using it (in fact, I had to look it up in Wikipedia now to learn what that letter is). An even better example than the rest of yours would be Kuß (German for the noun kiss), which only people above 30 (like me) still spell this way, but younger people spell Kuss since the official rules have changed over the last 10 years. In this particular case, you should definitely be prepared to handle "Kuss" and "Kuß" as legal input. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
Thank you guys! Works perfectly! :D Regards, Steve Rodriguez On Sat, Jul 12, 2014 at 1:21 AM, Peter Otten <__pete...@web.de> wrote: > Peter Otten wrote: > > > PS: You sometimes see > > > > message in "qQ" > > > > but this is buggy as it is true when the message is either > > "q", "Q", or "qQ". > > Oops, I forgot "". > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
Hi Steve, In your conditionals: … while message != 'q' or 'Q'/message != “q” or message != “Q”: … Python will only match the first variable. A better approach (which might be a good solution) would be capturing the exit commands in a list like this: JL’s code: while message not in [“q”, “Q”]: # blah, blah, your code… # code end Effectively, we’re testing if the command is a member of our exit commands list, and if it is, we’ll fall off the loop. Try this solution and see if it works for you. Cheers, Joseph ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
Steven D'Aprano Wrote in message: > On Sat, Jul 12, 2014 at 09:33:20AM +0100, Alan Gauld wrote: > >> 2) Better (IMHO) is to convert message to lower case (or upper if >> you prefer) and only do one comparison: >> >> while message.lower() != 'q': > > I second this advice, but with a slight modification. > > If you're using Python 3.3 or higher, it is better to use > message.casefold rather than lower. For English, there's no real > difference: > > py> "Hello World!".casefold() > 'hello world!' > > > but it can make a difference for non-English languages: > > py> "Große".lower() # German for "great" or "large" > 'große' > py> "Große".casefold() > 'grosse' > I don't remember my high school German enough to remember if the ß character is an example, but in various languages there are characters that exist only in uppercase, and whose lowercase equivalent is multiple letters. Or vice versa. And characters that have multiple valid spellings in uppercase, but only one in lowercase. If the latter is true for German, perhaps GROSSE and GROßE are valid uppercase, but only grosse for lowercase. -- DaveA ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
On Sat, Jul 12, 2014 at 11:27:17AM +0100, Alan Gauld wrote: > On 12/07/14 10:28, Steven D'Aprano wrote: > > >If you're using Python 3.3 or higher, it is better to use > >message.casefold rather than lower. For English, there's no real > >difference: > >... > >but it can make a difference for non-English languages: > > > >py> "Große".lower() # German for "great" or "large" > >'große' > >py> "Große".casefold() > >'grosse' > > You learn something new etc... > > But I'm trying to figure out what difference this makes in > practice? > > If you were targeting a German audience wouldn't you just test > against the German alphabet? After all you still have to expect 'grosse' > which isn't English, so if you know to expect grosse > why not just test against große instead? Because the person might have typed any of: grosse GROSSE gROSSE große Große GROßE GROẞE etc., and you want to accept them all, just like in English you'd want to accept any of GREAT great gREAT Great gReAt etc. Hence you want to fold everything to a single, known, canonical version. Case-fold will do that, while lowercasing won't. (The last example includes a character which might not be visible to many people, since it is quite unusual and not supported by many fonts yet. If it looks like a box or empty space for you, it is supposed to be capital sharp-s, matching the small sharp-s ß.) Oh, here's another example of the difference, this one from Greek: py> 'Σσς'.lower() # three versions of sigma 'σσς' py> 'Σσς'.upper() 'ΣΣΣ' py> 'Σσς'.casefold() 'σσσ' I suspect that there probably aren't a large number of languages where casefold and lower do something different, since most languages don't have distinguish between upper and lower case at all. But there's no harm in using it, since at worst it returns the same as lower(). -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
On 12/07/14 10:28, Steven D'Aprano wrote: If you're using Python 3.3 or higher, it is better to use message.casefold rather than lower. For English, there's no real difference: ... but it can make a difference for non-English languages: py> "Große".lower() # German for "great" or "large" 'große' py> "Große".casefold() 'grosse' You learn something new etc... But I'm trying to figure out what difference this makes in practice? If you were targeting a German audience wouldn't you just test against the German alphabet? After all you still have to expect 'grosse' which isn't English, so if you know to expect grosse why not just test against große instead? I think I'm missing something. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
On Sat, Jul 12, 2014 at 09:33:20AM +0100, Alan Gauld wrote: > 2) Better (IMHO) is to convert message to lower case (or upper if > you prefer) and only do one comparison: > > while message.lower() != 'q': I second this advice, but with a slight modification. If you're using Python 3.3 or higher, it is better to use message.casefold rather than lower. For English, there's no real difference: py> "Hello World!".casefold() 'hello world!' but it can make a difference for non-English languages: py> "Große".lower() # German for "great" or "large" 'große' py> "Große".casefold() 'grosse' -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
On 11/07/14 22:16, Steve Rodriguez wrote:
Hey guys n gals,
New to python, having some problems with while loops, I would like to
make a program quick once q or Q is typed, but thus far I can only get
the first variable to be recognized.
> My code looks like:
>
> message = raw_input("-> ")
> while message != 'q':
Peter has given a comprehensive reply.
There are two other options he didn't mention.
1) Use 'and' instead of 'or':
while message != 'q' and message != 'Q':
2) Better (IMHO) is to convert message to lower case (or upper if
you prefer) and only do one comparison:
while message.lower() != 'q':
HTH,
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.flickr.com/photos/alangauldphotos
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Re: [Tutor] While loop issue, variable not equal to var or var
Peter Otten wrote: > PS: You sometimes see > > message in "qQ" > > but this is buggy as it is true when the message is either > "q", "Q", or "qQ". Oops, I forgot "". ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop issue, variable not equal to var or var
Steve Rodriguez wrote:
> Hey guys n gals,
>
> New to python, having some problems with while loops, I would like to make
> a program quick once q or Q is typed, but thus far I can only get the
> first variable to be recognized. My code looks like:
>
> message = raw_input("-> ")
> while message != 'q':
> s.send(message)
> data = s.recv(2048)
> print str(data)
> message = raw_input("-> ")
> s.close()
> print("Shutting Down")
>
> I've tried:
>
> while message != 'q' or 'Q':
This evaluates
(message != "q") or "Q"
and "Q" is always True in a boolean context:
>>> bool("Q")
True
> while message != 'q' or message != 'Q':
This is true when at least one of the subexpressions
message != "q"
message != "Q"
is True. When the value of message is "q" it must be unequal to "Q" and vice
versa, so there is always at least one true subexpression.
> while message != ('q' or 'Q'):
When you try the right side in the interactive interpreter you get
>>> "q" or "Q"
'q'
so this is the same as just
message != "q"
> Any ideas would be much appreciated! Thanks! :D
while message.lower() != "q":
while message not in ("q", "Q"):
while message != "q" and message != "Q":
There's another one that chains boolean expressions
while "q" != message != "Q":
that I don't recommend here but that is very readable for checking number
intervals:
if 0 <= some_number < 1:
print some_number, "is in the half-open interval [0,1)"
You also may consider an infinite loop:
while True:
message = raw_input("-> ")
if message in ("q", "Q"):
break
s.send(message)
...
This avoids the duplicate raw_input().
PS: You sometimes see
message in "qQ"
but this is buggy as it is true when the message is either
"q", "Q", or "qQ".
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[Tutor] While loop issue, variable not equal to var or var
Hey guys n gals,
New to python, having some problems with while loops, I would like to make
a program quick once q or Q is typed, but thus far I can only get the first
variable to be recognized. My code looks like:
message = raw_input("-> ")
while message != 'q':
s.send(message)
data = s.recv(2048)
print str(data)
message = raw_input("-> ")
s.close()
print("Shutting Down")
I've tried:
while message != 'q' or 'Q':
while message != 'q' or message != 'Q':
while message != ('q' or 'Q'):
Any ideas would be much appreciated! Thanks! :D
Regards,
Steve Rodriguez
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Re: [Tutor] While Loop?
On 18/05/14 23:44, Sam Ball wrote: I however would like to add in another line that tells the user their account is invalid before looping around and asking them to re enter their account. OK, Time to introdusce another Pyhon idioM, the break clause. while True: # loop forever get input from user check/convert input if no errors: break # exits the loop print error message here "Please Input Your Account Number:") userAccountNumber = int(userAccount) As for users typing in a name like "Charlie" or a float I would like that to spit out an error also, but I haven't learned how to accomplish that yet. The code you have will detect the error and throw an exception. To stay in the loop you need to catch those exceptions in a try/except clause. while True: try: get input check/convert input break except error1, error2,: print error messages here If you haven't covered try/except yet then you should read up on it as it has several variations and subtleties. HTH -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While Loop?
> Firstly thanks everyone for the help, I definitely learned something.
> The current version of Python I'm using is actually version 3, sorry for not
> specifying that earlier.
> I ended up going with Alan's suggestion and created the below code which
> works perfectly fine.
> I however would like to add in another line that tells the user their account
> is invalid
> before looping around and asking them to re enter their account.
>
> userAccount = ''
> while len (userAccount) !=8:
>userAccount = input ("Please Input Your Account Number:")
>userAccountNumber = int(userAccount)
>
>
> As for users typing in a name like "Charlie" or a float I would like that to
> spit out
> an error also, but I haven't learned how to accomplish that yet.
>
> Thanks again.
----
> Date: Wed, 14 May 2014 16:16:45 -0400
> From: d...@davea.name
> To: tutor@python.org
> Subject: Re: [Tutor] While Loop?
>
> On 05/14/2014 05:45 AM, Sam Ball wrote:
>> I'm attempting to create a program where the user inputs their account
>> number (which must be 8 digits) and if what the user enters is not 8 digits
>> in length I want python to tell the user this is invalid and then keep
>> asking for the account number until a suitable number has been entered.
>> I'm guessing it's a sort of while loop but I'm not 100% sure as I'm quite
>> new to Python.
>>
>
> Welcome to Python, and to the Tutor mailing list. Please post in text
> form, as the html you're now using is quite error prone, especially
> since this is a text list. There's no errors I can see with your
> present message, but it's a good habit to learn early - tell your email
> program to use "plain text".
>
> Next, it's very important to specify what version of Python you're
> using. In particular there are differences between Python version 2.x
> and version 3.x And those differences affect the input statement.
>
> From your print syntax, it appears you're aiming at Python 2.x But
> it's not valid there either, so it's better if you be explicit in your
> question.
>
>
>> So far I have...
>>
>>
>>
>>
>> userAccountNumber = eval(input("Please Input Your Account Number:"))
>
> Since I'm asssuming Python 2.x, you want int(raw_input( instead.
> input() in 2.x is a security mistake, and eval() is for either version
> of Python.
>
>
>> while userAccountNumber> 1 or <=999:
>
> Syntax error, as you've discovered. Alan has told you how to fix it.
> But it would be much better to get in the habit of quoting the entire
> error message (it's called a traceback) instead of paraphrasing it.
>
>> print userAccountNumber ("Invalid Account Number! Account Must Be Eight
>> Digits")
>
> Once you've fixed the above, you'll get an error on this line. But how
> to fix it depends on what Python version you're using.
> userAccountNumber isn't a function, so why are you trying to call it?
>
> Next problem is that your loop doesn't ask the user again, it just loops
> around trying to print its error message.
>>
>>
>>
>> When I run this however it gives me an invalid syntax and highlights the =
>> in <=999:
>>
>> Would appreciate any help with sorting this out.
>>
>
> Once you've gone as far as you can get with these suggestions from Alan,
> Danny, and me, be sure and use reply-list to post your next revision and
> query. (Or, if your email program doesn't support that, use Reply-All,
> and remove from the header everyone you don't want to get the response).
> And of course, you'll tell us what version of Python you're
> taqrgeting. In particular, keep the tutor@python.org recipient.
>
> Once your program works, you need to consider other things, possible
> bugs. For example, what happends if a user types "charlie" instead of
> a number? Or if they type a floating point value? What would you like
> to happen?
>
> --
> DaveA
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Re: [Tutor] While Loop?
On 05/14/2014 05:45 AM, Sam Ball wrote:
I'm attempting to create a program where the user inputs their account number
(which must be 8 digits) and if what the user enters is not 8 digits in length
I want python to tell the user this is invalid and then keep asking for the
account number until a suitable number has been entered.
I'm guessing it's a sort of while loop but I'm not 100% sure as I'm quite new
to Python.
Welcome to Python, and to the Tutor mailing list. Please post in text
form, as the html you're now using is quite error prone, especially
since this is a text list. There's no errors I can see with your
present message, but it's a good habit to learn early - tell your email
program to use "plain text".
Next, it's very important to specify what version of Python you're
using. In particular there are differences between Python version 2.x
and version 3.x And those differences affect the input statement.
From your print syntax, it appears you're aiming at Python 2.x But
it's not valid there either, so it's better if you be explicit in your
question.
So far I have...
userAccountNumber = eval(input("Please Input Your Account Number:"))
Since I'm asssuming Python 2.x, you want int(raw_input( instead.
input() in 2.x is a security mistake, and eval() is for either version
of Python.
while userAccountNumber > 1 or <=999:
Syntax error, as you've discovered. Alan has told you how to fix it.
But it would be much better to get in the habit of quoting the entire
error message (it's called a traceback) instead of paraphrasing it.
print userAccountNumber ("Invalid Account Number! Account Must Be Eight
Digits")
Once you've fixed the above, you'll get an error on this line. But how
to fix it depends on what Python version you're using.
userAccountNumber isn't a function, so why are you trying to call it?
Next problem is that your loop doesn't ask the user again, it just loops
around trying to print its error message.
When I run this however it gives me an invalid syntax and highlights the = in
<=999:
Would appreciate any help with sorting this out.
Once you've gone as far as you can get with these suggestions from Alan,
Danny, and me, be sure and use reply-list to post your next revision and
query. (Or, if your email program doesn't support that, use Reply-All,
and remove from the header everyone you don't want to get the response).
And of course, you'll tell us what version of Python you're
taqrgeting. In particular, keep the tutor@python.org recipient.
Once your program works, you need to consider other things, possible
bugs. For example, what happends if a user types "charlie" instead of
a number? Or if they type a floating point value? What would you like
to happen?
--
DaveA
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Re: [Tutor] While Loop?
On Wed, May 14, 2014 at 2:45 AM, Sam Ball wrote:
> I'm attempting to create a program where the user inputs their account
> number (which must be 8 digits) and if what the user enters is not 8 digits
> in length I want python to tell the user this is invalid and then keep
> asking for the account number until a suitable number has been entered.
> I'm guessing it's a sort of while loop but I'm not 100% sure as I'm quite
> new to Python.
>
> So far I have...
>
>
>
> userAccountNumber = eval(input("Please Input Your Account Number:"))
Don't use eval here. If you want to turn a string that's full of
digits into a number, use int()
https://docs.python.org/3/library/functions.html#int
eval() is dangerous. Don't use it.
> while userAccountNumber > 1 or <=999:
> print userAccountNumber ("Invalid Account Number! Account Must Be Eight
> Digits")
>
> When I run this however it gives me an invalid syntax and highlights the =
> in <=999:
>
> Would appreciate any help with sorting this out.
The compiler is technically correct: it's invalid syntax.
You've written something that scans as English. But it does not scan
as a Python program. "or" does not have the English meaning in
Python.
To put it another way: what are you comparing to be less than or equal
to ? You've left that implicit. Many programming languages
do not allow implicit statements because it's too easy to
misunderstand or misinterpret.
Make what you're comparing explicit.
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Re: [Tutor] While Loop?
On 14/05/14 10:45, Sam Ball wrote:
I'm attempting to create a program where the user inputs their account
number (which must be 8 digits) and if what the user enters is not 8
digits in length I want python to tell the user this is invalid and then
keep asking for the account number until a suitable number has been entered.
I'm guessing it's a sort of while loop
You guess correct
userAccountNumber = eval(input("Please Input Your Account Number:"))
But please don;t do this. it is a huge security hole since whatever your
user enters will be executed as Python code - thats what eval() does.
Your user can ytype anything in there.
The correct approach is to use raw_input (since you seem to be using
Pthon v2) and a conversion function such as int() to get the data
type that you want.
while userAccountNumber > 1 or <=999:
Python sees this as:
while (userAccountNumber > 1) or <=999:
Which makes no sense.
In most programming languages you test this like this:
(userAccountNumber > 1) or (userAccountNumber <= 999):
But in Python you can do these compound checks more
succinctly like this:
> while not (999 < userAccountNumber < 1):
And the other way is to check the length of the input at source:
userAccount = ''
while len(userAccount) != 8:
userAccount = raw_input("Please Input Your Account Number:")
userAccountNumber = int(userAccount)
HTH
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.flickr.com/photos/alangauldphotos
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[Tutor] While Loop?
I'm attempting to create a program where the user inputs their account number
(which must be 8 digits) and if what the user enters is not 8 digits in length
I want python to tell the user this is invalid and then keep asking for the
account number until a suitable number has been entered.
I'm guessing it's a sort of while loop but I'm not 100% sure as I'm quite new
to Python.
So far I have...
userAccountNumber = eval(input("Please Input Your Account Number:"))
while userAccountNumber > 1 or <=999:
print userAccountNumber ("Invalid Account Number! Account Must Be Eight
Digits")
When I run this however it gives me an invalid syntax and highlights the = in
<=999:
Would appreciate any help with sorting this out.
Thank you.
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Re: [Tutor] while loop
On 01/04/14 00:22, Scott Dunning wrote:
def print_n(s,n):
i = 0
while i < n:
print s,
i += 1
print_n('a',3)
Also, with this exercise it’s using a doctest so I don’t actually call the
function
I have no idea what you mean buy this?
There is no doctest above and you do call the function...
so I can’t figure out a way to make the string’s print on
> separate lines without changing the doctest code?
You don't have any doctest code and the printing on one line
is a result of the comma in the print statement.
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.flickr.com/photos/alangauldphotos
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Re: [Tutor] while loop
Scott Dunning Wrote in message:
>
> On Mar 31, 2014, at 5:15 AM, Dave Angel wrote:
>>
>> Do you know how to define and initialize a second local variable?
>> Create one called i, with a value zero.
>>
>> You test expression will not have a literal, but compare the two
>> locals. And the statement that increments will change i, not
>> n.
>
> So like this?
> def print_n(s,n):
> i = 0
> while i < n:
> print s,
> i += 1
>
> print_n('a',3)
>
> So this is basically making i bigger by +1 every time the while loop passes
> until it passes n, then it becomes false right?
>
> Also, with this exercise itâs using a doctest so I donât actually call
> the function so I canât figure out a way to make the stringâs print on
> separate lines without changing the doctest code?
>
The trailing comma on the print statement is suppressing the
newline that's printed by default. If you want them on separate
lines, get rid of the comma.
--
DaveA
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Re: [Tutor] while loop
On Mar 31, 2014, at 5:15 AM, Dave Angel wrote:
>
> Do you know how to define and initialize a second local variable?
> Create one called i, with a value zero.
>
> You test expression will not have a literal, but compare the two
> locals. And the statement that increments will change i, not
> n.
So like this?
def print_n(s,n):
i = 0
while i < n:
print s,
i += 1
print_n('a',3)
So this is basically making i bigger by +1 every time the while loop passes
until it passes n, then it becomes false right?
Also, with this exercise it’s using a doctest so I don’t actually call the
function so I can’t figure out a way to make the string’s print on separate
lines without changing the doctest code?
Thanks for all of the help!
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Re: [Tutor] while loop
On Mar 31, 2014, at 1:39 AM, Mark Lawrence wrote: > > They say that the truth hurts, so if that's the best you can come up with, I > suggest you give up programming :( You’re in the TUTOR section. People in here are new to programming. I’ve only been doing this for a couple months and I just learned about while loops two days ago. If my questions are annoying you I suggest you not read them. : ( ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
On Mar 31, 2014, at 2:01 AM, Alan Gauld wrote: > > Incidentally, your assignment does not appear to require > a while loop, just iteration? If thats the case you could > use a for loop instead and it would actually be more > suitable. Have you covered for loops yet? > No, we haven’t got to for loops yet, that’s why it needs to be done with a while for now. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
* Scott Dunning [2014-03-30 18:37]: > Without out a break or placing that 10 in there I can’t think of a way > to have the while loop stop once it reaches (n). Any hints? As discussed already, you can't use fixed values (ie, you don't know that 10 is always going to be there). > def print_n(s, n): > > while n <= 10: > > print s > > n = n + 1 > > So, instead of while n <= 10: Think about: while something <= n: and changing something and retesting. -- David Rock da...@graniteweb.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
Scott Dunning Wrote in message: > > On Mar 30, 2014, at 4:29 AM, Dave Angel wrote: >> >> You're getting closer. Remember that the assignment shows your >> function being called with 10, not zero. So you should have a >> separate local variable, probably called I, which starts at >> zero, and gets incremented each time. >> >> The test in the while should be comparing them. >> > So, this is what I have now and it âworksâ but, instead of printing (s) > on seperate lines theyâre all on the same line? > > def print_n(s,n): > while n < 10: > print s * n > break > assert isinstance(s, str) > assert isinstance(n, int) > > So much for getting closer. Go back to the version I replied to. Do you know how to define and initialize a second local variable? Create one called i, with a value zero. You test expression will not have a literal, but compare the two locals. And the statement that increments will change i, not n. -- DaveA ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
On 31/03/14 03:13, Scott Dunning wrote: separate local variable, probably called I, which starts at zero, and gets incremented each time. The test in the while should be comparing them. So, this is what I have now and it ‘works’ It doesn't work because they are all on the same line. But also because it does NOT use iteration. Your while loop is completely redundant. You could remove the while and break lines and it would do exactly the same. def print_n(s,n): while n < 10: print s * n break You're other attempt where you increment n is much closer to what is being asked for. The only difference is you need to modify the while test to not use a hard coded 10 but use the parameter instead. Then use a separate value to do the counting. Incidentally, your assignment does not appear to require a while loop, just iteration? If thats the case you could use a for loop instead and it would actually be more suitable. Have you covered for loops yet? -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
On 31/03/14 02:37, Scott Dunning wrote: You're getting closer. Remember that the assignment shows your function being called with 10, not zero. So you should have a separate local variable, probably called I, which starts at zero, and gets incremented each time. Without out a break or placing that 10 in there I can’t think > of a way to have the while loop stop once it reaches (n). Dave has explained in his first paragraph(above) how to do it. n is a parameter in your function so the value is passed in by the caller. You should not be using a literal 10 you should be using n, since that's the required number of repeats. Then you need to create a new local variable in your function and let that variable count up until it equals whatever n is. That's where the iteration comes in. And as you count up, towards n, print s. hth -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
On 31/03/2014 03:13, Scott Dunning wrote: On Mar 30, 2014, at 4:29 AM, Dave Angel wrote: You're getting closer. Remember that the assignment shows your function being called with 10, not zero. So you should have a separate local variable, probably called I, which starts at zero, and gets incremented each time. The test in the while should be comparing them. So, this is what I have now and it ‘works’ but, instead of printing (s) on seperate lines they’re all on the same line? def print_n(s,n): while n < 10: print s * n break assert isinstance(s, str) assert isinstance(n, int) They say that the truth hurts, so if that's the best you can come up with, I suggest you give up programming :( -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
On Mar 30, 2014, at 4:29 AM, Dave Angel wrote: > > You're getting closer. Remember that the assignment shows your > function being called with 10, not zero. So you should have a > separate local variable, probably called I, which starts at > zero, and gets incremented each time. > > The test in the while should be comparing them. > So, this is what I have now and it ‘works’ but, instead of printing (s) on seperate lines they’re all on the same line? def print_n(s,n): while n < 10: print s * n break assert isinstance(s, str) assert isinstance(n, int) ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
On Mar 30, 2014, at 4:29 AM, Dave Angel wrote:
>
>
> You're getting closer. Remember that the assignment shows your
> function being called with 10, not zero. So you should have a
> separate local variable, probably called I, which starts at
> zero, and gets incremented each time.
The exercise just asks to print (s), (n) times using iteration. The exersise
is in a doctest which I didn’t really understand at first. So, I guess while I
was doing it “correctly” it wasn’t what the exercise is asking for. This I
guess is what the doctest is looking for.
"""Print the string `s`, `n` times.
Parameters
--
s -- A string
n -- an integer, the number of times to
print `s'
Examples
>>> print_n("hello", 3)
hello
hello
hello
>>> print_n("bye", 0)
>>> print_n("a", 6)
a
a
a
a
a
a
"""
>
> The test in the while should be comparing them.
>
> Note that the number of times is specified in top level code, and
> implemented in the function. You should not have a literal 10 in
> the function.
Without out a break or placing that 10 in there I can’t think of a way to have
the while loop stop once it reaches (n). Any hints?
SCott
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Re: [Tutor] while loop
Scott Dunning Wrote in message:
>
> On Mar 29, 2014, at 12:47 AM, Dave Angel wrote:
>>
>> So did your code print the string 10 times? When asking for help,
>> it's useful to show what you tried, and what was expected, and
>> what actually resulted.
>>
>> You use * to replicate the string, but that wasn't what the
>> assignment asked for. So take out the *n part. You're supposed to
>> use iteration, specifically the while loop.
>>
>> Your while loop doesn't quit after 10 times, it keeps going. Can
>> you figure out why?
>
> This works without a break. Is this more a long the line of what the
> excercise was looking for you think?
>>
> def print_n(s, n):
> while n <= 10:
> print s
> n = n + 1
>
> print_n("hello\n", 0)
>
>
>
You're getting closer. Remember that the assignment shows your
function being called with 10, not zero. So you should have a
separate local variable, probably called I, which starts at
zero, and gets incremented each time.
The test in the while should be comparing them.
Note that the number of times is specified in top level code, and
implemented in the function. You should not have a literal 10 in
the function.
--
DaveA
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Re: [Tutor] while loop
On 30/03/14 02:36, Scott Dunning wrote:
Your while loop doesn't quit after 10 times, it keeps going. Can
you figure out why?
This works without a break.
> Is this more a long the line of what the excercise was
> looking for you think?
Yes.
while n <= 10:
print s
n = n + 1
Python while loops effectively come in two patterns:
1) while some condition
do stuff
modify the test condition
2) while True:
if some condition:
break
else
do stuff
The first version is actually the intended use of while from a computing
science point of view.
The second one, which creates an infinite loop and then breaks
out of it is a bit of a kluge which pure structured programming
theory says is bad practice. It has become idiomatic in Python
however, because it often avoids another bad practice, namely
repeating yourself.
For example if we only used the first pattern we often
need to do this:
display_menu()
choice = input('pick a choice: ')
while choice != 'quit':
if choice == 'save':
do_save()
elif choice == ...
display_menu()
choice = input('pick a choice: ')
Notice how we have to have the menu/input pair
both before and inside the loop.
We can avoid that using the infinite loop version:
while True:
display_menu()
choice = input('pick a choice: ')
if choice == 'quit'
break
elif choice == 'save':
do_save()
elif choice == ...
So we have effectively chosen the lesser of two evils.
Compromising on computer science purity is not unusual
in the real world of programming.
In your example there was no need to repeat code so
you could use the uncompromised, pure while loop with
an effective test condition. In that case you can and
should modify the test condition variables inside
the loop, which is what you did with the n = n+1 line.
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.flickr.com/photos/alangauldphotos
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Re: [Tutor] while loop
On Mar 29, 2014, at 12:47 AM, Dave Angel wrote:
>
> So did your code print the string 10 times? When asking for help,
> it's useful to show what you tried, and what was expected, and
> what actually resulted.
>
> You use * to replicate the string, but that wasn't what the
> assignment asked for. So take out the *n part. You're supposed to
> use iteration, specifically the while loop.
>
> Your while loop doesn't quit after 10 times, it keeps going. Can
> you figure out why?
This works without a break. Is this more a long the line of what the excercise
was looking for you think?
>
def print_n(s, n):
while n <= 10:
print s
n = n + 1
print_n("hello\n", 0)
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Re: [Tutor] while loop
On Mar 29, 2014, at 12:47 AM, Dave Angel wrote:
>
> What are you uncertain about, assert or isinstance? Such
> statements are frequently used to make sure the function
> arguments are of the right type.
I’m not sure exactly what it’s doing. I guess I need to read up on it again.
>
>>
>>
>> This is what I have so far but I’m not really sure it’s what the excersise
>> is asking for?
>>
>> n = 5
>> def print_n(s, n):
>> while n > 0:
>> print s * n
>>
>> print_n("hello", 10)
>>
>
> So did your code print the string 10 times? When asking for help,
> it's useful to show what you tried, and what was expected, and
> what actually resulted.
Yes it repeated forever, I put a break after the print statement.
>
> You use * to replicate the string, but that wasn't what the
> assignment asked for. So take out the *n part. You're supposed to
> use iteration, specifically the while loop.
That’s where I was confused, I wasn’t sure how to get the while loop to work
just the n times and then stop.
>
> Your while loop doesn't quit after 10 times, it keeps going. Can
> you figure out why?
>
I understand why it didn’t stop after 10 times, because I said while n is
greater than 0 print s, and I have the value of n as 5 so it will never stop,
that’s why I added a break after the print statement. I’m sure there is a
better way , I’m just not seeing it. Any hints?
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Re: [Tutor] while loop
On Mar 28, 2014, at 10:36 PM, Ben Finney wrote:
>
> A good programming exercise will show an example input and the expected
> output, to give an unambiguous test case. Does the homework have that?
This is what the exercise has as examples…
"""Print the string `s`, `n` times.
Parameters
--
s -- A string
n -- an integer, the number of times to
print `s'
Examples
>>> print_n("hello", 3)
hello
hello
hello
>>> print_n("bye", 0)
>>> print_n("a", 6)
a
a
a
a
a
a
"""
assert isinstance(s, str)
assert isinstance(n, int)
#TODO: Implement the function
>
> If not, you're unfortunately left to your own interpretation of what the
> requirements mean.
>
I’m not sure what assert isinstance means?
This is what I have, it works but I’m not sure it’s what the exercise is asking
for.
n = 5
def print_n(s, n):
while n > 0:
print s * n
break
print_n("hello\n", 10)
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Re: [Tutor] while loop
Scott W Dunning Wrote in message:
>
> On Mar 28, 2014, at 9:54 PM, Scott W Dunning wrote:
>
>> Hello, Iâm working on some practice exercises from my homework and Iâm
>> having some issues figuring out what is wanted.
>>
>> Weâre working with the while loop and this is what the question states;
>>
>> Write a function print_n that prints a string n times using iteration.
>>
>> """Print the string `s`, `n` times.
>>
>>
>> This is also in the exercises and Iâm not sure what it means and why
>> itâs there.
>>
>> assert isinstance(s, str)
>> assert isinstance(n, int)
What are you uncertain about, assert or isinstance? Such
statements are frequently used to make sure the function
arguments are of the right type.
>
>
> This is what I have so far but Iâm not really sure itâs what the
> excersise is asking for?
>
> n = 5
> def print_n(s, n):
>while n > 0:
>print s * n
>
> print_n("hello", 10)
>
So did your code print the string 10 times? When asking for help,
it's useful to show what you tried, and what was expected, and
what actually resulted.
You use * to replicate the string, but that wasn't what the
assignment asked for. So take out the *n part. You're supposed to
use iteration, specifically the while loop.
Your while loop doesn't quit after 10 times, it keeps going. Can
you figure out why?
--
DaveA
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Re: [Tutor] while loop
On 03/29/2014 01:18 AM, Scott W Dunning wrote:
On Mar 28, 2014, at 9:54 PM, Scott W Dunning wrote:
Hello, I’m working on some practice exercises from my homework and I’m having
some issues figuring out what is wanted.
We’re working with the while loop and this is what the question states;
Write a function print_n that prints a string n times using iteration.
"""Print the string `s`, `n` times.
This is also in the exercises and I’m not sure what it means and why it’s there.
assert isinstance(s, str)
assert isinstance(n, int)
Any help is greatly appreciated!
Scott
This is what I have so far but I’m not really sure it’s what the excersise is
asking for?
n = 5
def print_n(s, n):
while n > 0:
print s * n
print_n("hello", 10)
Scott,
Are required to use a while loop?
Two ways to solve this, while loop and for in range loop
while loop
n = 5
s = 'some string'
def while_print(s, n):
index = o
while index < n:
print(index, s)
index += 1
def alternative_print(s, n):
for index in range(0, n):
print(index, s)
The while loop requires that a counter variable or some loop exit
condition so you do not end up in an endless loop. This is a common
problem with while loops in programming, not just Python. So, if there
is alternative method of looping available, good programming practice is
to avoid a while loop in any language. The for loop version
automatically iterates over the range from 0 to n-1 (5 times). I
included the index variable in the print to show the increase of the index.
The results for both:
0 some string
1 some string
2 some string
3 some string
4 some string
--
Jay Lozier
jsloz...@gmail.com
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[Tutor] while loop
Hello, I’m working on some practice exercises from my homework and I’m having some issues figuring out what is wanted. We’re working with the while loop and this is what the question states; Write a function print_n that prints a string n times using iteration. """Print the string `s`, `n` times. This is also in the exercises and I’m not sure what it means and why it’s there. assert isinstance(s, str) assert isinstance(n, int) Any help is greatly appreciated! Scott ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
Scott W Dunning writes: > On Mar 28, 2014, at 9:54 PM, Scott W Dunning wrote: > > > We’re working with the while loop and this is what the question states; > > > > Write a function print_n that prints a string n times using iteration. > This is what I have so far but I’m not really sure it’s what the > excersise is asking for? A good programming exercise will show an example input and the expected output, to give an unambiguous test case. Does the homework have that? If not, you're unfortunately left to your own interpretation of what the requirements mean. -- \ “Truth would quickly cease to become stranger than fiction, | `\ once we got as used to it.” —Henry L. Mencken | _o__) | Ben Finney ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop
On Mar 28, 2014, at 9:54 PM, Scott W Dunning wrote:
> Hello, I’m working on some practice exercises from my homework and I’m having
> some issues figuring out what is wanted.
>
> We’re working with the while loop and this is what the question states;
>
> Write a function print_n that prints a string n times using iteration.
>
> """Print the string `s`, `n` times.
>
>
> This is also in the exercises and I’m not sure what it means and why it’s
> there.
>
> assert isinstance(s, str)
> assert isinstance(n, int)
>
>
> Any help is greatly appreciated!
>
> Scott
This is what I have so far but I’m not really sure it’s what the excersise is
asking for?
n = 5
def print_n(s, n):
while n > 0:
print s * n
print_n("hello", 10)
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Re: [Tutor] While loop
# skip 5
if count == 5:
continue # means "Jump back to the top of the looop"
It is the reason. You yourself have mentioned it right inside the code!
On 7 April 2013 09:40, Dave Angel wrote:
> On 04/06/2013 11:23 PM, Najam Us Saqib wrote:
>
>> Hi,
>>
>> Would you please help me by explaining that why " 5 " is skipped and not
>> printed in the following program?
>>
>>
> Seems to me the comments say it pretty well. The continue statement
> causes execution to continue at the while statement, which has the effect
> of skipping the print. Like Monopoly: go directly to jail, do not pass go.
>
>
> Thank you.
>> Najam.
>>
>> count = 0
>> while True:
>> count += 1
>> # end loop if count is greater than 10
>> if count > 10:
>> break # means "break out of the loop"
>> # skip 5
>> if count == 5:
>> continue # means "Jump back to the top of the looop"
>> print count
>>
>> raw_input("\n\nPress the enter key to exit.")
>>
>> Output:
>>
>> 1
>> 2
>> 3
>> 4
>> 6
>> 7
>> 8
>> 9
>> 10
>>
>>
>> Press the enter key to exit.
>>
>
> Incidentally, this looks like a transliteration of something written for
> some other language. An experienced Python programmer would never write it
> this way.
>
> I'd use something like (untested):
>
> for count in xrange(11):
> if count != 5:
> print count
>
> On the other hand, a course --teaching a C programmer to use Python--
> might well use this as an early example, showing you later how much
> elegantly it can be done.
>
>
> --
> DaveA
> __**_
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>
--
--
*Sayan Chatterjee*
Dept. of Physics and Meteorology
IIT Kharagpur
Lal Bahadur Shastry Hall of Residence
Room AB 205
Mob: +91 9874513565
blog: www.blissprofound.blogspot.com
Volunteer , Padakshep
www.padakshep.org
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Re: [Tutor] While loop
On 04/06/2013 11:23 PM, Najam Us Saqib wrote:
Hi,
Would you please help me by explaining that why " 5 " is skipped and not
printed in the following program?
Seems to me the comments say it pretty well. The continue statement
causes execution to continue at the while statement, which has the
effect of skipping the print. Like Monopoly: go directly to jail, do
not pass go.
Thank you.
Najam.
count = 0
while True:
count += 1
# end loop if count is greater than 10
if count > 10:
break # means "break out of the loop"
# skip 5
if count == 5:
continue # means "Jump back to the top of the looop"
print count
raw_input("\n\nPress the enter key to exit.")
Output:
1
2
3
4
6
7
8
9
10
Press the enter key to exit.
Incidentally, this looks like a transliteration of something written for
some other language. An experienced Python programmer would never write
it this way.
I'd use something like (untested):
for count in xrange(11):
if count != 5:
print count
On the other hand, a course --teaching a C programmer to use Python--
might well use this as an early example, showing you later how much
elegantly it can be done.
--
DaveA
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Re: [Tutor] While loop
On 04/06/2013 11:23 PM, Najam Us Saqib wrote:
Hi,
Would you please help me by explaining that why " 5 " is skipped and not
printed in the following program?
Seems to me the comments say it pretty well. The continue statement
causes execution to continue at the while statement, which has the
effect of skipping the print. Like Monopoly: go directly to jail, do
not pass go.
Thank you.
Najam.
count = 0
while True:
count += 1
# end loop if count is greater than 10
if count > 10:
break # means "break out of the loop"
# skip 5
if count == 5:
continue # means "Jump back to the top of the looop"
print count
raw_input("\n\nPress the enter key to exit.")
Output:
1
2
3
4
6
7
8
9
10
Press the enter key to exit.
Incidentally, this looks like a transliteration of something written for
some other language. An experienced Python programmer would never write
it this way.
I'd use something like (untested):
for count in xrange(11):
if count != 5:
print count
On the other hand, a course --teaching a C programmer to use Python--
might well use this as an early example, showing you later how much
elegantly it can be done.
--
DaveA
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[Tutor] While loop
Hi,
Would you please help me by explaining that why " 5 " is skipped and not
printed in the following program?
Thank you.
Najam.
count = 0
while True:
count += 1
# end loop if count is greater than 10
if count > 10:
break # means "break out of the loop"
# skip 5
if count == 5:
continue # means "Jump back to the top of the looop"
print count
raw_input("\n\nPress the enter key to exit.")
Output:
1
2
3
4
6
7
8
9
10
Press the enter key to exit.___
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Re: [Tutor] While Loop
On 06/13/2012 01:29 AM, Andrew Brunn wrote:
> Let me preface by saying that I am currently taking my first programming
> class; so I have been a "programmer" for just over a week now.
>
> Here is my question;
>
> I
> am trying to create a while loop that will allow me ask for a username
> and password. If a wrong username and password is entered, I would like
> the program to prompt the user to re-enter the username and password
> until they get it correct. That means even if they get it wrong a
> thousand times, I want to program to keep asking them.
>
> This is my code;
>
> [code]
> username = ""
>
> while not username:
> username=raw_input("Username: ")
>
> password = ""
>
> while not password:
>
> password=raw_input("Password: ")
> if username == "john doe" and password == "fopwpo":
> print "Login successful"
> else:
> print "Error. Please re-enter your username and password."
> [code]
>
>
>
> Andy Brunn
>
So put the whole thing in a while loop. For that matter, also put it in
a function. Anything over about 3 lines should be written as one or
more functions.
The simplest change would be to make the while loop look likewhile
True:, and put a break right after the print "Login successful" line,
def getUserPass():
while True
(existing code here)
if username == "" and password == "":
print "login successful"
break
else:
print "Error: Please "
--
DaveA
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[Tutor] While Loop
Let me preface by saying that I am currently taking my first programming
class; so I have been a "programmer" for just over a week now.
Here is my question;
I
am trying to create a while loop that will allow me ask for a username
and password. If a wrong username and password is entered, I would like
the program to prompt the user to re-enter the username and password
until they get it correct. That means even if they get it wrong a
thousand times, I want to program to keep asking them.
This is my code;
[code]
username = ""
while not username:
username=raw_input("Username: ")
password = ""
while not password:
password=raw_input("Password: ")
if username == "john doe" and password == "fopwpo":
print "Login successful"
else:
print "Error. Please re-enter your username and password."
[code]
Andy Brunn___
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Re: [Tutor] while loop ends prematurly
Hi again, On 2 January 2012 06:28, Steven D'Aprano wrote: >> Another answer is to use Decimal class, which CAN represent decimal values >> exactly. > > > That only applies to decimal values which can be represented using a fixed > number of decimal places. So 1/5 is fine, and is 0.2 exactly, but 1/3 is > not, since it would require an infinite number of decimal places. It's occurred to me that I should've probably used the term "exact decimal" in my comment, so please read it as such. (The general class of decimals include 3 types of decimals: exact, recurring and non-recurring. Generally when people use the word decimal they tend to mean "exact decimals". Apologies for not being clearer.) Walter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop ends prematurly
(You accidentally forgot to include the list when you replied. The easiest way (for most people) to avoid that is to use Reply-all) On 01/02/2012 01:00 AM, Sarma Tangirala wrote: On 2 Jan 2012 08:56, "Dave Angel" wrote: Easiest answer is to use integers. Scale everything up by a factor of 100, and you won't need floats at all. Just convert when printing (and even then you may get into trouble). Just to add a bit here. I've seen a couple of people do it this way - subtract the two numbers and check if the result is above a particular threshold value, and if so they are not equal. That was also in that Fortran reference from '67. The trick on that is to subtract, and compare the absolute value to an epsilon value. if abs(a-b)< threshold: equals-logic goes here else: unequals-logic goes here It can get tricky to pick a good threshold. In this case, a thousandth of a penny is clearly enough. But for many programs the threshold also has to be calculated. In APL, this comparison logic is automated, via a concept called fuzz. You typically specify the fuzz value once, and the threshold is automatically calculated by something like multiplying fuzz by the larger (in absolute value) of the two numbers being compared. These approaches are also tricky, and when they fail, debugging them can be very difficult. Another answer is to use Decimal class, which CAN represent decimal values exactly. When I implemented the microcode math package for a processor (which predated microprocessors like the 8080 and 8086), it was all decimal. We had decimal logic in the hardware for adding two-digit integers, everything more complicated was a loop in the microcode. With that system, if you printed out a value, you saw an exact equivalent of what was stored internally. -- DaveA ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop ends prematurly
Hi Steven, On 2 January 2012 06:28, Steven D'Aprano wrote: > That only applies to decimal values which can be represented using a fixed > number of decimal places. So 1/5 is fine, and is 0.2 exactly, but 1/3 is > not, since it would require an infinite number of decimal places. Just a small nit pick with the above: 1/3 is however not a decimal number. The word decimal means "tenth part", decimal numbers are generally defined/understood as numbers that are expressible as decimal fractions, meaning numbers where the denominator is a power of 10 or is an exact "tenth part". Understood as such, decimal numbers are therefore obviously accurately representable by the Decimal class which is the whole point of calling the class "Decimal". To backtrack slightly, numbers like 1/3, 1/5 etc are in general called common or vulgar fractions, the only requirement being that they have an integer numerator and an integer non-zero denominator. The class of numbers representible like this is called rational numbers and the test for whether a number can be called rational is whether it can be written as such. The set of numbers we refer to as decimal numbers then, are a subset of rational numbers, the test for whether they can be called decimal being whether they can be written as a rational number with the additional requirement that the denominator be a power of ten. Addtionally, any rational number with a denominator of which the prime factors are 2 and 5 may therefore be rewritten as a decimal number, thus we know that 2/5 can also be accurately represented by a decimal number (since the prime factors of 5 is 5), as can 1/50 (since the prime factors of 50 are 2,5,5), but 1/3 can not, since 3 has only 3 as its prime factor (and not 2 or 5), and neither 1/24 (since the prime factors are 2,2,2,3). So an additional test for whether a given rational number can be accurately rewritten as a decimal (tenth part) number, is to inspect the prime factors of the denominator. If this consists solely of 2's and 5's it can be expressed as a decimal, if any other factors are present then it cannot be accurately expressed as a decimal. A happy and prosperous 2012 to all, Walter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop ends prematurly
Dave Angel wrote: Easiest answer is to use integers. Scale everything up by a factor of 100, and you won't need floats at all. Just convert when printing (and even then you may get into trouble). Another answer is to use Decimal class, which CAN represent decimal values exactly. That only applies to decimal values which can be represented using a fixed number of decimal places. So 1/5 is fine, and is 0.2 exactly, but 1/3 is not, since it would require an infinite number of decimal places. BTW, if this is supposed to represent US legal tender, you left out the fifty-cent piece as well as the two dollar bill. http://kowb1290.com/our-two-cents-on-the-two-dollar-bill/ -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop ends prematurly
On Mon, Jan 2, 2012 at 3:48 AM, brian arb wrote: > Hello, > Can some please explain this to me? > My while loop should continue while "owed" is greater than or equal to "d" > > first time the function is called > the loop exits as expected > False: 0.00 >= 0.01 > the next time it does not > False: 0.01 >= 0.01 > > Below is the snippet of code, and the out put. > > Thanks! > > def make_change(arg): > denom = [100.0, 50.0, 20.0, 10.0, 5.0, 1.0, 0.25, 0.10, 0.05, 0.01] > owed = float(arg) > payed = [] > for d in denom: > while owed >= d: > owed -= d > b = owed >= d > print '%s: %f >= %f' % (b, owed, d) > payed.append(d) > print sum(payed), payed > return sum(payed) > > if __name__ == '__main__': > values = [21.48, 487.69] #, 974.41, 920.87, 377.93, 885.12, 263.47, > 630.91, 433.23, 800.58] > for i in values: > make_change(i)) > > > False: 1.48 >= 20.00 > False: 0.48 >= 1.00 > False: 0.23 >= 0.25 > True: 0.13 >= 0.10 > False: 0.03 >= 0.10 > True: 0.02 >= 0.01 > True: 0.01 >= 0.01 > False: 0.00 >= 0.01 > 21.48 [20.0, 1.0, 0.25, 0.1, 0.1, 0.01, 0.01, 0.01] > True: 387.69 >= 100.00 > True: 287.69 >= 100.00 > True: 187.69 >= 100.00 > False: 87.69 >= 100.00 > False: 37.69 >= 50.00 > False: 17.69 >= 20.00 > False: 7.69 >= 10.00 > False: 2.69 >= 5.00 > True: 1.69 >= 1.00 > False: 0.69 >= 1.00 > True: 0.44 >= 0.25 > False: 0.19 >= 0.25 > False: 0.09 >= 0.10 > False: 0.04 >= 0.05 > True: 0.03 >= 0.01 > True: 0.02 >= 0.01 > False: 0.01 >= 0.01 > 487.68 [100.0, 100.0, 100.0, 100.0, 50.0, 20.0, 10.0, 5.0, 1.0, 1.0, 0.25, > 0.25, 0.1, 0.05, 0.01, 0.01, 0.01] > What happened is that you ran into the weirdness that we call the IEEE 754-2008 standard, otherwise known as floating point numbers. in quite simple terms, the way the computer represents floating point numbers means that inaccuracies sneak in when performing math on them, and some numbers can't even be represented correctly, like 0.1. You can notice this in some of the simplest calculations: >>> 0.1 0.1 >>> # seems normal? Well, python is actually tricking you. Let's force it to >>> show us this number with some more accuracy: >>> "%.32f" % 0.1 # force it to show 32 digits after the period '0.1555111512312578' >>> # whoops! that's not quite 0.1 at all! let's try some more: >>> 9 * 0.1 0.9 >>> 0.9 0.9 >>> 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 0.8999 >>> "%.32f" % 0.9 '0.90002220446049250313' >>> # what?! those aren't even the same numbers!! >>> 0.1 + 0.2 0.30004 >>> # what the hell? Usually this doesn't really matter, because we don't really care about what happens after you get way far into the decimal spaces. But when you compare for equality, which is what you're doing here, this stuff can bite you in the ass real ugly. If you replace the %f with %.32f in that debugging statement, you'll see why the loop bails: False: 0.0077 >= 0.0100 That kinda sucks, doesn't it? floating point errors are hard to find, especially since python hides them from you sometimes. But there is a simple solution! Multiply all numbers by 100 inside that function and then simply work with integers, where you do get perfect accuracy. HTH, Hugo P.S.: this problem is not in inherent to python but to the IEEE standard. The sacrifice in accuracy was made deliberately to keep floating point numbers fast, so it's by design and not something that should be "fixed." Pretty much all languages that use floats or doubles have the same thing. If you really want decimal numbers, there is a Decimal class in Python that implements 100% accurate decimal numbers at the cost of performance. Look it up. P.P.S.: for more information you should read these. The first link is a simple explanation. The second is more complicated, but obligatory reading material for every programmer worth his salts: the floating point guide: http://floating-point-gui.de/ what every computer scientist should know about floating-point arithmetic: http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop ends prematurly
On 01/01/2012 09:48 PM, brian arb wrote: Hello, Can some please explain this to me? My while loop should continue while "owed" is greater than or equal to "d" first time the function is called the loop exits as expected False: 0.00>= 0.01 the next time it does not False: 0.01>= 0.01 Below is the snippet of code, and the out put. Thanks! def make_change(arg): denom = [100.0, 50.0, 20.0, 10.0, 5.0, 1.0, 0.25, 0.10, 0.05, 0.01] owed = float(arg) payed = [] for d in denom: while owed>= d: owed -= d b = owed>= d print '%s: %f>= %f' % (b, owed, d) payed.append(d) print sum(payed), payed return sum(payed) if __name__ == '__main__': values = [21.48, 487.69] #, 974.41, 920.87, 377.93, 885.12, 263.47, 630.91, 433.23, 800.58] for i in values: make_change(i)) False: 1.48>= 20.00 False: 0.48>= 1.00 False: 0.23>= 0.25 True: 0.13>= 0.10 False: 0.03>= 0.10 True: 0.02>= 0.01 True: 0.01>= 0.01 False: 0.00>= 0.01 21.48 [20.0, 1.0, 0.25, 0.1, 0.1, 0.01, 0.01, 0.01] True: 387.69>= 100.00 True: 287.69>= 100.00 True: 187.69>= 100.00 False: 87.69>= 100.00 False: 37.69>= 50.00 False: 17.69>= 20.00 False: 7.69>= 10.00 False: 2.69>= 5.00 True: 1.69>= 1.00 False: 0.69>= 1.00 True: 0.44>= 0.25 False: 0.19>= 0.25 False: 0.09>= 0.10 False: 0.04>= 0.05 True: 0.03>= 0.01 True: 0.02>= 0.01 False: 0.01>= 0.01 487.68 [100.0, 100.0, 100.0, 100.0, 50.0, 20.0, 10.0, 5.0, 1.0, 1.0, 0.25, 0.25, 0.1, 0.05, 0.01, 0.01, 0.01] You're using float values and pretending that they can accurately represent dollars and cents. 0.19 (for example) cannot be exactly represented in a float, and when you start adding up multiple of these, sooner or later the error will become visible. This is a problem with binary floating point, and I first encountered it in 1967, when the textbook for Fortran made an important point about never comparing floating point values for equals, as small invisible errors are bound to bite you. Easiest answer is to use integers. Scale everything up by a factor of 100, and you won't need floats at all. Just convert when printing (and even then you may get into trouble). Another answer is to use Decimal class, which CAN represent decimal values exactly. BTW, if this is supposed to represent US legal tender, you left out the fifty-cent piece as well as the two dollar bill. -- DaveA ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] while loop ends prematurly
Hello, Can some please explain this to me? My while loop should continue while "owed" is greater than or equal to "d" first time the function is called the loop exits as expected False: 0.00 >= 0.01 the next time it does not False: 0.01 >= 0.01 Below is the snippet of code, and the out put. Thanks! def make_change(arg): denom = [100.0, 50.0, 20.0, 10.0, 5.0, 1.0, 0.25, 0.10, 0.05, 0.01] owed = float(arg) payed = [] for d in denom: while owed >= d: owed -= d b = owed >= d print '%s: %f >= %f' % (b, owed, d) payed.append(d) print sum(payed), payed return sum(payed) if __name__ == '__main__': values = [21.48, 487.69] #, 974.41, 920.87, 377.93, 885.12, 263.47, 630.91, 433.23, 800.58] for i in values: make_change(i)) False: 1.48 >= 20.00 False: 0.48 >= 1.00 False: 0.23 >= 0.25 True: 0.13 >= 0.10 False: 0.03 >= 0.10 True: 0.02 >= 0.01 True: 0.01 >= 0.01 False: 0.00 >= 0.01 21.48 [20.0, 1.0, 0.25, 0.1, 0.1, 0.01, 0.01, 0.01] True: 387.69 >= 100.00 True: 287.69 >= 100.00 True: 187.69 >= 100.00 False: 87.69 >= 100.00 False: 37.69 >= 50.00 False: 17.69 >= 20.00 False: 7.69 >= 10.00 False: 2.69 >= 5.00 True: 1.69 >= 1.00 False: 0.69 >= 1.00 True: 0.44 >= 0.25 False: 0.19 >= 0.25 False: 0.09 >= 0.10 False: 0.04 >= 0.05 True: 0.03 >= 0.01 True: 0.02 >= 0.01 False: 0.01 >= 0.01 487.68 [100.0, 100.0, 100.0, 100.0, 50.0, 20.0, 10.0, 5.0, 1.0, 1.0, 0.25, 0.25, 0.1, 0.05, 0.01, 0.01, 0.01] ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while loop problem
mustafa akkoc wrote:
hello i have syntax problem in this program
After correcting the indentations, and putting a missing parentheses in
line 24 (the last line), I don't see any Syntax Error.
#!/usr/bin/python
# Filename: while.py
number = 23
running = True
while running :
guess= int(input('Enter an integer : ')) # it give a syntax error
this line can you me ?
if guess == number:
print('Congratulations, you guessed it.')
running = False # this causes the while loop to stop
elif guess < number:
print('No, it is a little higher than that.')
else:
print('No, it is a little lower than that.')
else:
print('The while loop is over.')
# Do anything else you want to do here
print('Done') # you missed a paren, probably CopyPasteError
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Re: [Tutor] while loop problem
"mustafa akkoc" wrote
hello i have syntax problem in this program
#!/usr/bin/python
# Filename: while.py
number = 23
running = True
while running :
guess= input('Enter an integer : ') # it give a syntax error this
line can
you me ?
Always post the full text of error messages please. It helps us a lot.
Howevbder in this case I suspect the problem is that you do not
seem to have indented the line under the while loop (although that
may be due to email reformatting issues...) But that should say
IndentationError not Syntax error?
Also you don;t say what version of Python you are using.
input() has changed slightly in v3...
HTH,
Alan G.
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[Tutor] while loop problem
hello i have syntax problem in this program
#!/usr/bin/python
# Filename: while.py
number = 23
running = True
while running :
guess= input('Enter an integer : ') # it give a syntax error this line can
you me ?
if guess == number:
print('Congratulations, you guessed it.')
running = False # this causes the while loop to stop
elif guess < number:
print('No, it is a little higher than that.')
else:
print('No, it is a little lower than that.')
else:
print('The while loop is over.')
# Do anything else you want to do here
print('Done'
--
Mustafa Akkoc
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Re: [Tutor] While loop counter
Thank you John & Allen, See the loops section of my tutorial for more about for and while loops. Yes, great tutorial, just getting it to sink in, now thats the problem :) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop counter
"David" <[EMAIL PROTECTED]> wrote Hi, I am trying to get a while loop that will execute 5 time then stop. Copngratulations, you have succeeded. Unfortunately nothing happens inside your loop. I suspect you actually want to execute some code 5 times? #counter = 0 #while counter < 5 : #counter = counter + 1 Yep, this would have done it. while True: mytime.tick() mytime.print_time() time.sleep(1) # Sleep for 1 second And this loop runs forever because you never break out of it. counter = 0 while counter < 5 : counter = counter + 1 If you did get out of the infinite loop above then this one does do it too. But all it does is increment the counter. If you want code to be executed it must also be inside the loop (ie inside the indented code section). So what I think you wanted would be: counter = 0 while counter < 5: mytime.tick() mytime.print_time() time.sleep(1) # Sleep for 1 second counter = counter + 1 But since its for a fixed number of iterations you are better off using a for loop: for counter in range(5) mytime.tick() mytime.print_time() time.sleep(1) # Sleep for 1 second Note we don't need to increment the counter in this version. See the loops section of my tutorial for more about for and while loops. HTH, -- Alan Gauld Author of the Learn to Program web site http://www.freenetpages.co.uk/hp/alan.gauld ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop counter
On 08/07/2008, David <[EMAIL PROTECTED]> wrote: > Hi, I am trying to get a while loop that will execute 5 time then stop. Hi David, The standard pattern is like this: i = 0 while i < 5: # the stuff you want to do goes here i = i + 1 Note that if you know exactly how many times you will execute your loop, you should use a for loop instead: for i in range(5): # the stuff you want to do goes here HTH! -- John. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] While loop counter
Hi, I am trying to get a while loop that will execute 5 time then stop.
#!/usr/bin/python
# Filename myfirstclass.py
#
# A Little digital clock
from time_class import Time
import sys
import time
mytime = Time()
print "Can you tell me the time (24h)?"
hour = input("Give the hour: ")
minute = input("Give the minutes: ")
second = input("Give the seconds: ")
mytime.set_time(hour, minute, second)
#counter = 0
#while counter < 5 :
#counter = counter + 1
while True:
mytime.tick()
mytime.print_time()
time.sleep(1) # Sleep for 1 second
counter = 0
while counter < 5 :
counter = counter + 1
Here is the class;
#!/usr/bin/python
# Filename: time_class.py
class Time:
def __init__(self):
self.__hour = 0
self.__minute = 0
self.__second = 0
def set_time(self, hour, minute, second):
self.set_hour(hour)
self.set_minute(minute)
self.set_second(second)
def set_hour(self, hour):
if 0 <= hour and hour < 24:
self.__hour = hour
def set_minute(self, minute):
if 0 <= minute and minute < 60:
self.__minute = minute
def set_second(self, second):
if 0 <= second and second < 60:
self.__second = second
def tick(self):
self.__second += 1
self.__minute += self.__second / 60
self.__hour += self.__minute / 60
self.__hour = self.__hour % 24
self.__minute = self.__minute % 60
self.__second = self.__second % 60
def print_time(self):
print '%02d:%02d:%02d' % (self.__hour, self.__minute, self.__second)
Thanks, very new to Python.
-david
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Re: [Tutor] while Loop
> -Original Message- > Subject: Re: [Tutor] while Loop > > Oops, didn't notice the uppercase U, thanks Luke. > > - Original Message - > Subject: Re: [Tutor] while Loop > > > >> define it with usedPocketsOne = 192000? > > no, I said UsedPocketsOne was not defined. Note the > different starting > > letter. > > Python is case senstitive, meaning usedPocketsOne is not > the same as > > UsedPocketsOne. > > So yes, you defined usedPocketsOne with the assignment to > 192000, but > > you did not define UsedPocketsOne. > > I've been out of the office for the last week, so I'm catching up. You might use something like PyChecker, PyLint, or PyFlakes. Those utilities would catch errors like this. I have a hotkey in VIM that kicks off PyFlakes on the current buffer. Also, I'm not 100% sure, but I think Komodo IDE would catch this as well. Mike ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while Loop
Oops, didn't notice the uppercase U, thanks Luke. - Original Message - From: "Luke Paireepinart" <[EMAIL PROTECTED]> To: "Darren Williams" <[EMAIL PROTECTED]> Cc: Sent: Wednesday, July 18, 2007 3:08 PM Subject: Re: [Tutor] while Loop > Darren Williams wrote: >> Luke and Kent, you're right, I didn't think JavaScript calculated >> multiplaction and division before addition and subtraction but seems >> it does :) >> >> I dunno what you mean about usedPocketsOne not being defined, didn't I >> define it with usedPocketsOne = 192000? > no, I said UsedPocketsOne was not defined. Note the different starting > letter. > Python is case senstitive, meaning usedPocketsOne is not the same as > UsedPocketsOne. > So yes, you defined usedPocketsOne with the assignment to 192000, but > you did not define UsedPocketsOne. > > Note what happens when I test your code: > >>> def main(): > > usedPocketsOne = 192000 > junkiesOne = 500 > labSpaceOne = 0 > > resultOne = 0 > while usedPocketsOne > (junkiesOne - labSpaceOne) * 17: > resultOne = resultOne + 1 > usedPocketsOne = (UsedPocketsOne - junkiesOne + labSpaceOne) * 17 > > > >>> main() > > Traceback (most recent call last): > File "", line 1, in -toplevel- >main() > File "", line 10, in main >usedPocketsOne = (UsedPocketsOne - junkiesOne + labSpaceOne) * 17 > NameError: global name 'UsedPocketsOne' is not defined > > You should get a similar error, unless you've somehow defined > UsedPocketsOne somewhere else. > HTH, > -Luke > > Correction of previous e-mail: This raises a NameError, not a > SyntaxError, as I said before. sorry about that. > > > ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while Loop
Darren Williams wrote: > Luke and Kent, you're right, I didn't think JavaScript calculated > multiplaction and division before addition and subtraction but seems > it does :) > > I dunno what you mean about usedPocketsOne not being defined, didn't I > define it with usedPocketsOne = 192000? no, I said UsedPocketsOne was not defined. Note the different starting letter. Python is case senstitive, meaning usedPocketsOne is not the same as UsedPocketsOne. So yes, you defined usedPocketsOne with the assignment to 192000, but you did not define UsedPocketsOne. Note what happens when I test your code: >>> def main(): usedPocketsOne = 192000 junkiesOne = 500 labSpaceOne = 0 resultOne = 0 while usedPocketsOne > (junkiesOne - labSpaceOne) * 17: resultOne = resultOne + 1 usedPocketsOne = (UsedPocketsOne - junkiesOne + labSpaceOne) * 17 >>> main() Traceback (most recent call last): File "", line 1, in -toplevel- main() File "", line 10, in main usedPocketsOne = (UsedPocketsOne - junkiesOne + labSpaceOne) * 17 NameError: global name 'UsedPocketsOne' is not defined You should get a similar error, unless you've somehow defined UsedPocketsOne somewhere else. HTH, -Luke Correction of previous e-mail: This raises a NameError, not a SyntaxError, as I said before. sorry about that. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while Loop
Luke and Kent, you're right, I didn't think JavaScript calculated multiplaction and division before addition and subtraction but seems it does :) I dunno what you mean about usedPocketsOne not being defined, didn't I define it with usedPocketsOne = 192000? - Original Message - From: "Luke Paireepinart" <[EMAIL PROTECTED]> To: "Darren Williams" <[EMAIL PROTECTED]> Cc: Sent: Wednesday, July 18, 2007 11:57 AM Subject: Re: [Tutor] while Loop > Darren Williams wrote: >> Hi all, >> I'm writing a calculator for an online game that I used to play but >> don't seem to be able to break out of the while loop, the program will >> just go over and over the loop, crashing the program and I don't know if >> Python is just really slow at this type of thing or i'm doing it >> completely wrong in Python (the equivalent code in JavaScript works >> fine). > I don't think you're doing it completely wrong, just partially :) > And I doubt that, if it's quick in Javascript, it will be any slower in > Python, since Javascript is interpreted as well, but by the browser while > it's simultaneously downloading the content of the webpage and rendering > it to the screen. > Also, I'm pretty sure the code here is not equivalent to the Javascript > code you included (specific remarks below.) >> Python code - >> def main(): >> usedPocketsOne = 192000 >> junkiesOne = 500 >> labSpaceOne = 0 >> resultOne = 0 >> while usedPocketsOne > (junkiesOne - labSpaceOne) * 17: > I don't know much about Javascript, but doesn't it have order of > operations? > For example, > usedPocketsOne > junkiesOne - labSpaceOne * 17 > is generally assumed to be > x = labSpaceOne * 17 > y = junkiesOne - x > usedPocketsOne > y > > > Whereas your Python equivalent, with the parenthesis, > usedPocketsOne > (junkiesOne - labSpaceOne) * 17 > > changes the order of operations (forces the subtraction before the > multiplication) > and hence changes the resulting value. That is, unless Javascript > evaluates left-to-right with no operator heirarchy (which I would be > saddened to learn, if it's true.) >> resultOne = resultOne + 1 >> usedPocketsOne = (UsedPocketsOne - junkiesOne + labSpaceOne) * 17 > This shouldn't even run - you should get a syntax error because > UsedPocketsOne is not defined anywhere else in the program (that you've > shown us.) > Perhaps you're running it in IDLE with no subprocess and some value for > UsedPocketsOne is hanging around (from previous edits of the program, or > interpreter session, or something else) and mucking up the works? > -Luke > > > ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while Loop
Darren Williams wrote: > Hi all, > > I'm writing a calculator for an online game that I used to play but > don't seem to be able to break out of the while loop, the program will > just go over and over the loop, crashing the program and I don't know > if Python is just really slow at this type of thing or i'm doing it > completely wrong in Python (the equivalent code in JavaScript works fine). I don't think you're doing it completely wrong, just partially :) And I doubt that, if it's quick in Javascript, it will be any slower in Python, since Javascript is interpreted as well, but by the browser while it's simultaneously downloading the content of the webpage and rendering it to the screen. Also, I'm pretty sure the code here is not equivalent to the Javascript code you included (specific remarks below.) > > Python code - > > def main(): > usedPocketsOne = 192000 > junkiesOne = 500 > labSpaceOne = 0 > > resultOne = 0 > while usedPocketsOne > (junkiesOne - labSpaceOne) * 17: I don't know much about Javascript, but doesn't it have order of operations? For example, usedPocketsOne > junkiesOne - labSpaceOne * 17 is generally assumed to be x = labSpaceOne * 17 y = junkiesOne - x usedPocketsOne > y Whereas your Python equivalent, with the parenthesis, usedPocketsOne > (junkiesOne - labSpaceOne) * 17 changes the order of operations (forces the subtraction before the multiplication) and hence changes the resulting value. That is, unless Javascript evaluates left-to-right with no operator heirarchy (which I would be saddened to learn, if it's true.) > resultOne = resultOne + 1 > usedPocketsOne = (UsedPocketsOne - junkiesOne + labSpaceOne) * 17 This shouldn't even run - you should get a syntax error because UsedPocketsOne is not defined anywhere else in the program (that you've shown us.) Perhaps you're running it in IDLE with no subprocess and some value for UsedPocketsOne is hanging around (from previous edits of the program, or interpreter session, or something else) and mucking up the works? -Luke ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] while Loop
Darren Williams wrote:
> Hi all,
>
> I'm writing a calculator for an online game that I used to play but
> don't seem to be able to break out of the while loop, the program will
> just go over and over the loop, crashing the program and I don't know if
> Python is just really slow at this type of thing or i'm doing it
> completely wrong in Python (the equivalent code in JavaScript works fine).
>
> Python code -
>
> def main():
> usedPocketsOne = 192000
> junkiesOne = 500
> labSpaceOne = 0
>
> resultOne = 0
> while usedPocketsOne > (junkiesOne - labSpaceOne) * 17:
> resultOne = resultOne + 1
> usedPocketsOne = (UsedPocketsOne - junkiesOne + labSpaceOne) * 17
Maybe this should be
usedPocketsOne = UsedPocketsOne - junkiesOne + labSpaceOne * 17
which is what you have in the JS.
Kent
> junkiesOne = junkiesOne + 1
>
> main()
>
> And the JavaScript equivalent (incase there are any stalwarts beside
> Alan here) -
>
> function main() {
> var usedPocketsOne = 192000
> var junkiesOne = 500
> var labSpaceOne = 0
>
> var resultOne = 0
> while (usedPocketsOne > junkiesOne - labSpaceOne * 17) {
> resultOne = resultOne + 1
> usedPocketsOne = usedPocketsOne - junkiesOne + labSpaceOne * 17
> junkiesOne = junkiesOne + 1
> }
> }
>
> Thanks in advance for any help :)
>
>
>
>
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[Tutor] while Loop
Hi all,
I'm writing a calculator for an online game that I used to play but don't seem
to be able to break out of the while loop, the program will just go over and
over the loop, crashing the program and I don't know if Python is just really
slow at this type of thing or i'm doing it completely wrong in Python (the
equivalent code in JavaScript works fine).
Python code -
def main():
usedPocketsOne = 192000
junkiesOne = 500
labSpaceOne = 0
resultOne = 0
while usedPocketsOne > (junkiesOne - labSpaceOne) * 17:
resultOne = resultOne + 1
usedPocketsOne = (UsedPocketsOne - junkiesOne + labSpaceOne) * 17
junkiesOne = junkiesOne + 1
main()
And the JavaScript equivalent (incase there are any stalwarts beside Alan here)
-
function main() {
var usedPocketsOne = 192000
var junkiesOne = 500
var labSpaceOne = 0
var resultOne = 0
while (usedPocketsOne > junkiesOne - labSpaceOne * 17) {
resultOne = resultOne + 1
usedPocketsOne = usedPocketsOne - junkiesOne + labSpaceOne * 17
junkiesOne = junkiesOne + 1
}
}
Thanks in advance for any help :)___
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Re: [Tutor] "while" loop for satisfing two conditions , advice requested
in understanding while loop someone should understand "if conditional" first.In "If conditional" there are common relational symbol "and" and "or"Let's discuss "and" conditional Condition 1 Condition 2 ResultTrue True TrueTrue False FalseFalse True False False False FalseIn short, and equal True if and only if both condition are true."If the while loop result condition is true it will execute its block." example:x = 1y = 1while x==1 and y==1: # it will be processed if x==1 and y==1 are both true, in this case it is!another example:x=1y=2while x==1 and y==1: # it will be processed if x==1 and y==1 are both true, in this case it is not! Hope this help!pujoOn 1/15/06, John Joseph <[EMAIL PROTECTED]> wrote: Hi I am trying to use "while" loop , here I wantwhile loop to check for two conditions , I am notgetting an idea how to use "while" loop for checkingtwo conditionsI used "&" condition , but it is not giving me the expected resultsI used in this way while (condition no 1) & (condition no2):print "Results" I request guidanceThanks Joseph John___NEW Yahoo! Cars - sell your car and browse thousands of new and used cars online! http://uk.cars.yahoo.com/___Tutor maillist - Tutor@python.orghttp://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] "while" loop for satisfing two conditions ,
> From: John Joseph <[EMAIL PROTECTED]> >I am trying to use while loop , here I want > while loop to check for two conditions , I am not > getting an idea how to use while loop for checking > two conditions > I used "&" condition , but it is not > giving me the expected results > I used in this way > > while (condition no 1) & (condition no2): > print Results Use 'and' instead of &. & is a bitwise logical AND - it operates on the individual bits of its arguments. 'and' treats the full operand as a logical value. The results can be different: >>> [1] & [2] Traceback (most recent call last): File "", line 1, in ? TypeError: unsupported operand type(s) for &: 'list' and 'list' >>> [1] and [2] [2] >>> 2 & 1 0 >>> 2 and 1 1 Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] "while" loop for satisfing two conditions , advice requested
Hi >while (condition no 1) & (condition no2): > print "Results" > While (condition no 1) and (condition no2): print "Results" in python you use the words and, or, not, is like: if myvar1 is not None and myvar2 == '1': print 'what a nice snowing day!' Carlo what is ITER? www.iter.org ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] "while" loop for satisfing two conditions , advice requested
Hi I am trying to use while loop , here I want while loop to check for two conditions , I am not getting an idea how to use while loop for checking two conditions I used "&" condition , but it is not giving me the expected results I used in this way while (condition no 1) & (condition no2): print Results I request guidance Thanks Joseph John ___ NEW Yahoo! Cars - sell your car and browse thousands of new and used cars online! http://uk.cars.yahoo.com/ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] While loop exercise
. , hotmail.com> writes: > I just finished the chapter which includes while loop, if-else-elif > structure and randrange(). > > Can anyone suggest me 3 exercises to remind of the chapter? The standard exercise which includes all three would be a number guessing game where the computer picks a number and the user guesses it (the opposite is also possible, but then randrange is not useful). A while loop is standard in *any* program that can be executed more than once. E.g. asking someone for a string is a single line of code, but asking for an unlimited number of strings directly requires a while loop. > Looking forward to writing some programs! At this stage there aren't many really useful application you can make, but you should use your fantasy. Pick a subject you know something about and make a simple application for it. I think there are lots of suitable subjects in maths, physics and children's games, but you can find suitable subjects in lots of other fields too. Other possible small programs using while and if (randrange is a bit exotic and not that useful): - let the user input names and dates of birth. Calculate membership fee to a club based on whether the person is a child, an adult or a senior citizen. - a quadradic formula solver (would have to check whether the determinant < 0) - a hangman game - a free fall calculator (given an object that is dropped from a certain height, calculate a table with its position as a function of time) - a quiz program about some topic you like (could even use randrange in this one to pick questions) - a program which combines some of the programs above - e.g. allow the user to play either number guessing or hangman. - a hotel booking application which allows making reservations for one or 2-person rooms and applies a discount if the reservation is on a day between monday and thursday. Yours, Andrei ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] While loop exercise
Hi, I just finished the chapter which includes while loop, if-else-elif structure and randrange(). Can anyone suggest me 3 exercises to remind of the chapter? Exercises shouldn't be too difficult because i'm newbie! Looking forward to writing some programs! Thanks. _ FREE pop-up blocking with the new MSN Toolbar - get it now! http://toolbar.msn.click-url.com/go/onm00200415ave/direct/01/ ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
