Re: [Tutor] dealing with user input whose value I don't know
On Fri, Oct 3, 2008 at 9:45 AM, David [EMAIL PROTECTED] wrote: Here is the code: def main(): import string Hey, lagging a bit behind the list, import string is unnecessary, mate. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
Omer [EMAIL PROTECTED] wrote Here is the code: def main(): import string import string is unnecessary, mate. Not entirely true since the code uses string.split() However since the split method of the string could be used instead then that would indeed render the import unnecessary. But you need both changes. Alan G ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
Hello Alan, dear list members,
Alan Gauld wrote:
The solution you have already seen - use string.split(',') to separate
the string into substrings and then convert each substring to an
integer.
This I have now done by using eval(). But now I wonder whether that is
actually clever because it is supposed to be similarly problematic as
the input() function in terms of security. Alternatively I could use
int() -- would that be the way forward?
Here is the code:
def main():
import string
print This program takes the average of numbers you supply!!
amount = raw_input(How many numbers do you want me to work with? )
print You want me to take the average of, amount, numbers.
numbers = raw_input(Please type the numbers, separated by commas: )
print You want to know the average of the numbers:, numbers
add = 0
for numStr in string.split(numbers, ,):
convNum = eval(numStr) # convert digit string to a number
add = add + convNum # add number to variable 'add'
print The sum of your numbers is:, add
average = add / float(amount)
print Therefore the average of your numbers is, average
main()
Many thanks,
David
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Re: [Tutor] dealing with user input whose value I don't know
David [EMAIL PROTECTED] wrote the string into substrings and then convert each substring to an integer. This I have now done by using eval(). But now I wonder whether that is actually clever because it is supposed to be similarly problematic as the input() function in terms of security. Absolutely. The more open and general you make your code the more opportunity you provide for attacks. Converting to int/float is much safer. -- 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] dealing with user input whose value I don't know
On Thu, Oct 2, 2008 at 12:06 PM, David [EMAIL PROTECTED] wrote: Hello, I am trying to do some exercises in John Zelle's book (chapter 4). I got stuck: Write a program that finds the average of a series of numbers entered by the user. The program should first ask the user how many numbers there are. Note: the average should always be a float, even if the user inputs are all ints. Okay, I can ask how many number are to be added: numbers = input(How many number do you want me to calculate? ) If I then get a reply, say 5, what I would have to do next is to ask for the five numbers so that I can calculate the average. But given that I don't know the the value of 'numbers' ex ante, how could I ask for the right amount of numbers? I don't see how this can be achieved with the tools I have learned so far... I am currently thinking along the lines of ans1, ans2 = input(Enter the numbers separated by a comma: ) average = (ans1 + ans2) / 2.0 But as I say - I don't know how many assignment there have to be, nor do I know how Python could then create these assignments. This is a common issue beginners to programming have. The question you ask yourself here is do I really need a direct reference in code to all my values? It appears to me that you don't. For example, how would you do this in real life? would you say x = num1 x2 = num2 x3 = num3 ... xn = numn x + x2 + x3 + x4 ... + xn / n or would you do this: 1 + 2 + 3 + 4 + 5 / count I would do the latter. It's the same way in programming. You can create these generic collections of items in Python. They are called lists. I'm a little pressed for time (i have a class starting in a few minutes) but this example should hopefully spark something in 'ya. a = [] b = [1,2,3,4,5] for item in b: a.append(item) Does that give you a hint about how you can add items to a collection without caring how many you have? Note that you can also do something like this (this is a bigger hint) a = [] b = [1,2,3,4,5] for i in range(len(b)): a.append(b[i]) Good luck! It would be great if someone could guide me towards the right track!! Thanks, David ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
On Fri, Oct 03, 2008 at 01:06:29AM +0800, David wrote: Hello, I am trying to do some exercises in John Zelle's book (chapter 4). I got stuck: Okay, I can ask how many number are to be added: numbers = input(How many number do you want me to calculate? ) If I then get a reply, say 5, what I would have to do next is to ask for the five numbers so that I can calculate the average. But given that I don't know the the value of 'numbers' ex ante, how could I ask for the right amount of numbers? You don't need to know in advance what the value of numbers will be. You can have Python iterate number times, asking for an additional number each time. You could add each to a variable (so it accumulates the sum as you iterate) and then divide by number. You could collect everything in a list and then do the calculation. There's a couple of ideas. See where that leads you and let us know. -- Steve Willoughby| Using billion-dollar satellites [EMAIL PROTECTED] | to hunt for Tupperware. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
[EMAIL PROTECTED] wrote on 10/02/2008 01:06:29 PM: Hello, I am trying to do some exercises in John Zelle's book (chapter 4). I got stuck: Write a program that finds the average of a series of numbers entered by the user. The program should first ask the user how many numbers there are. Note: the average should always be a float, even if the user inputs are all ints. Okay, I can ask how many number are to be added: numbers = input(How many number do you want me to calculate? ) you should really use raw_input to get the info from the user, and then convert it to a number. numbers=int(raw_input(How many number do you want me to calculate? )) If I then get a reply, say 5, what I would have to do next is to ask for the five numbers so that I can calculate the average. Write the code like you knew it was going to be a 5 and then replace anywhere the 5 appears with the variable 'numbers'. But given that I don't know the the value of 'numbers' ex ante, how could I ask for the right amount of numbers? I don't see how this can be achieved with the tools I have learned so far... Looking at the table of contents it looks like you should have learned about loops by now. I am currently thinking along the lines of ans1, ans2 = input(Enter the numbers separated by a comma: ) average = (ans1 + ans2) / 2.0 have each number be its own input and repeat it depending on how their input for numbers, and then do the averaging at the end. But as I say - I don't know how many assignment there have to be, nor do I know how Python could then create these assignments. you don't need to keep the individual numbers only the sum, but if you want to, use a list and append each new number to the end of the list. It would be great if someone could guide me towards the right track!! Thanks, David ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
Hello Christopher, [EMAIL PROTECTED] wrote: Okay, I can ask how many number are to be added: numbers = input(How many number do you want me to calculate? ) you should really use raw_input to get the info from the user, and then convert it to a number. numbers=int(raw_input(How many number do you want me to calculate? )) Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? Thanks, David ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
On Fri, Oct 03, 2008 at 01:38:48AM +0800, David wrote: Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? Depends on how you look at it. input() automatically evaluates whatever the user types as a Python expression and returns the result. So if they type 5, the integer 5 is returned. For your program, that's probably what you want, and has the advantage of letting you type something like 2+3 so your user can let Python evaluate math expressions. On the other hand, you'd think that you could ask a user for a text response using input(): name = input(What is your name? ) print Hello, , name But if they just type the answer, Python will crash with an error because it's expecting a legal Python expression there (so a string value would have to be typed in quotes). However, raw_input() will just return the characters the user typed without doing anything to them. Great for string values, but this means to get an integer result you'll have to pass that into the int() constructor function. IIRC Python 3.0 will actually make input() do what raw_input() today does, because this is confusing to people as it stands now. -- Steve Willoughby| Using billion-dollar satellites [EMAIL PROTECTED] | to hunt for Tupperware. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
On Thu, Oct 02, 2008, Steve Willoughby wrote: On Fri, Oct 03, 2008 at 01:38:48AM +0800, David wrote: Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? Depends on how you look at it. input() automatically evaluates whatever the user types as a Python expression and returns the result. So if they type 5, the integer 5 is returned. For your program, that's probably what you want, and has the advantage of letting you type something like 2+3 so your user can let Python evaluate math expressions. On the other hand, you'd think that you could ask a user for a text response using input(): name = input(What is your name? ) print Hello, , name But if they just type the answer, Python will crash with an error because it's expecting a legal Python expression there (so a string value would have to be typed in quotes). Remember the cardinal rule NEVER TRUST USER INPUT! Always check for validity, and use methods that prevent malicious strings from allowing the user to get unauthorized access or change things they shouldn't. Many of the common exploits of web pages are the result of poor checking of input resulting in sql injection attacks, and other breaches. Bill -- INTERNET: [EMAIL PROTECTED] Bill Campbell; Celestial Software LLC URL: http://www.celestial.com/ PO Box 820; 6641 E. Mercer Way Voice: (206) 236-1676 Mercer Island, WA 98040-0820 Fax:(206) 232-9186 There are three kinds of men. The ones that learn by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves. -- Will Rogers ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
Cheers for the insights! However, I just found out that changing input() to raw_input() breaks my code: This program takes the average of numbers you supply!! How many numbers do you want me to work with? 2 You want me to take the average of 2 numbers. Please type the numbers, separated by commas: 1,2 You want to know the average of the numbers: 1,2 Traceback (most recent call last): File avgInput.py, line 13, in module add = add + i TypeError: unsupported operand type(s) for +: 'int' and 'str' End of process output The reason being, I take, that numbers = raw_input(Please type the numbers, separated by commas: ) also returns the comma (1,2) and thus the for loop can't cope... So should I therefore retain numbers = input(Please type the numbers, separated by commas: ) ? Otherwise I don't know (yet) what to do David Bill Campbell wrote: On Thu, Oct 02, 2008, Steve Willoughby wrote: On Fri, Oct 03, 2008 at 01:38:48AM +0800, David wrote: Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? Depends on how you look at it. input() automatically evaluates whatever the user types as a Python expression and returns the result. So if they type 5, the integer 5 is returned. For your program, that's probably what you want, and has the advantage of letting you type something like 2+3 so your user can let Python evaluate math expressions. On the other hand, you'd think that you could ask a user for a text response using input(): name = input(What is your name? ) print Hello, , name But if they just type the answer, Python will crash with an error because it's expecting a legal Python expression there (so a string value would have to be typed in quotes). Remember the cardinal rule NEVER TRUST USER INPUT! Always check for validity, and use methods that prevent malicious strings from allowing the user to get unauthorized access or change things they shouldn't. Many of the common exploits of web pages are the result of poor checking of input resulting in sql injection attacks, and other breaches. Bill ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
On Thu, Oct 02, 2008 at 10:54:56AM -0700, Bill Campbell wrote:
Remember the cardinal rule NEVER TRUST USER INPUT! Always check
for validity, and use methods that prevent malicious strings from
allowing the user to get unauthorized access or change things
they shouldn't.
Yes, I probably should have qualified what I said. This is
VERY important. Should you ever allow input() or other eval()
of what the user typed (or for that matter, passing what the
user types into file operations, SQL queries, etc)? Yes, but
*only* if you are *certain* you *must* and that you know exactly
what you're doing. And probably not even then if you can
avoid it.
So the point was what the difference was between raw_input()
and input(), but Bill's right, don't just use input() or
eval() (and input() is essentially eval(raw_input())) casually.
Not sure why?
Suppose you put a program up for public use which gets a
string value using input(). Instead of
How many numbers? 5
the user types:
How many numbers? os.system('rm -rf /')
Don't ever assume data is safe or valid if it came from
outside your realm of control.
(And don't fool yourself that a script is just for me, in
most environments things get reused in ways you don't expect,
and even if not, get used to good programming habits).
--
Steve Willoughby| Using billion-dollar satellites
[EMAIL PROTECTED] | to hunt for Tupperware.
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Re: [Tutor] dealing with user input whose value I don't know
On Fri, Oct 03, 2008 at 02:06:47AM +0800, David wrote: Cheers for the insights! However, I just found out that changing input() to raw_input() breaks my code: Recall that we told you raw_input() returns a string, while input() returns an integer if you typed an integer value. So you need to convert the string of characters the user typed into an integer value before using it as a number: numbers = int(raw_input(...)) This program takes the average of numbers you supply!! How many numbers do you want me to work with? 2 You want me to take the average of 2 numbers. Please type the numbers, separated by commas: 1,2 You want to know the average of the numbers: 1,2 Traceback (most recent call last): File avgInput.py, line 13, in module add = add + i TypeError: unsupported operand type(s) for +: 'int' and 'str' End of process output The reason being, I take, that numbers = raw_input(Please type the numbers, separated by commas: ) also returns the comma (1,2) and thus the for loop can't cope... So should I therefore retain numbers = input(Please type the numbers, separated by commas: ) ? Otherwise I don't know (yet) what to do David Bill Campbell wrote: On Thu, Oct 02, 2008, Steve Willoughby wrote: On Fri, Oct 03, 2008 at 01:38:48AM +0800, David wrote: Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? Depends on how you look at it. input() automatically evaluates whatever the user types as a Python expression and returns the result. So if they type 5, the integer 5 is returned. For your program, that's probably what you want, and has the advantage of letting you type something like 2+3 so your user can let Python evaluate math expressions. On the other hand, you'd think that you could ask a user for a text response using input(): name = input(What is your name? ) print Hello, , name But if they just type the answer, Python will crash with an error because it's expecting a legal Python expression there (so a string value would have to be typed in quotes). Remember the cardinal rule NEVER TRUST USER INPUT! Always check for validity, and use methods that prevent malicious strings from allowing the user to get unauthorized access or change things they shouldn't. Many of the common exploits of web pages are the result of poor checking of input resulting in sql injection attacks, and other breaches. Bill ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor -- Steve Willoughby| Using billion-dollar satellites [EMAIL PROTECTED] | to hunt for Tupperware. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
I am not sure how you got from the input to your variable i, it is a good idea to post your code as well. That said raw_input will return the user's input as a string which you then need to convert to integers. So the commas are brought in as well. You can solve this in a couple of ways: First, you can split the string on the commas and get a list of strings each representing one of the numbers. numberlist=numbers.splt(,) will give you: numberslist=[1,2] which you can then loop over and convert to integers and add up. Secondly, you can have the users input the numbers one at a time inside the loop. add = add + int(raw_input(Please type the next number:)) Chris David [EMAIL PROTECTED] Sent by: [EMAIL PROTECTED] 10/02/2008 02:06 PM To tutor@python.org, [EMAIL PROTECTED] cc Subject Re: [Tutor] dealing with user input whose value I don't know Cheers for the insights! However, I just found out that changing input() to raw_input() breaks my code: This program takes the average of numbers you supply!! How many numbers do you want me to work with? 2 You want me to take the average of 2 numbers. Please type the numbers, separated by commas: 1,2 You want to know the average of the numbers: 1,2 Traceback (most recent call last): File avgInput.py, line 13, in module add = add + i TypeError: unsupported operand type(s) for +: 'int' and 'str' End of process output The reason being, I take, that numbers = raw_input(Please type the numbers, separated by commas: ) also returns the comma (1,2) and thus the for loop can't cope... So should I therefore retain numbers = input(Please type the numbers, separated by commas: ) ? Otherwise I don't know (yet) what to do David Bill Campbell wrote: On Thu, Oct 02, 2008, Steve Willoughby wrote: On Fri, Oct 03, 2008 at 01:38:48AM +0800, David wrote: Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? Depends on how you look at it. input() automatically evaluates whatever the user types as a Python expression and returns the result. So if they type 5, the integer 5 is returned. For your program, that's probably what you want, and has the advantage of letting you type something like 2+3 so your user can let Python evaluate math expressions. On the other hand, you'd think that you could ask a user for a text response using input(): name = input(What is your name? ) print Hello, , name But if they just type the answer, Python will crash with an error because it's expecting a legal Python expression there (so a string value would have to be typed in quotes). Remember the cardinal rule NEVER TRUST USER INPUT! Always check for validity, and use methods that prevent malicious strings from allowing the user to get unauthorized access or change things they shouldn't. Many of the common exploits of web pages are the result of poor checking of input resulting in sql injection attacks, and other breaches. Bill ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
Hello Steve, thanks for all your help and comments. What happens, though, is that with numbers = int(raw_input(Please type the numbers, separated by commas: )) my code is still defunct (whereas input() works): Please type the numbers, separated by commas: 1,2 Traceback (most recent call last): File avgInput.py, line 8, in module numbers = int(raw_input(Please type the numbers, separated by commas: )) ValueError: invalid literal for int() with base 10: '1,2' End of process output Here is the entire code: print This program takes the average of numbers you supply!! amount = raw_input(How many numbers do you want me to work with? ) print You want me to take the average of, amount, numbers. numbers = int(raw_input(Please type the numbers, separated by commas: )) print You want to know the average of the numbers:, numbers add = 0 for i in numbers: add = add + i print The sum of your numbers is:, add average = add / float(amount) print Therefore the average of your numbers is, average David Steve Willoughby wrote: On Fri, Oct 03, 2008 at 02:06:47AM +0800, David wrote: Cheers for the insights! However, I just found out that changing input() to raw_input() breaks my code: Recall that we told you raw_input() returns a string, while input() returns an integer if you typed an integer value. So you need to convert the string of characters the user typed into an integer value before using it as a number: numbers = int(raw_input(...)) This program takes the average of numbers you supply!! How many numbers do you want me to work with? 2 You want me to take the average of 2 numbers. Please type the numbers, separated by commas: 1,2 You want to know the average of the numbers: 1,2 Traceback (most recent call last): File avgInput.py, line 13, in module add = add + i TypeError: unsupported operand type(s) for +: 'int' and 'str' End of process output The reason being, I take, that numbers = raw_input(Please type the numbers, separated by commas: ) also returns the comma (1,2) and thus the for loop can't cope... So should I therefore retain numbers = input(Please type the numbers, separated by commas: ) ? Otherwise I don't know (yet) what to do David Bill Campbell wrote: On Thu, Oct 02, 2008, Steve Willoughby wrote: On Fri, Oct 03, 2008 at 01:38:48AM +0800, David wrote: Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? Depends on how you look at it. input() automatically evaluates whatever the user types as a Python expression and returns the result. So if they type 5, the integer 5 is returned. For your program, that's probably what you want, and has the advantage of letting you type something like 2+3 so your user can let Python evaluate math expressions. On the other hand, you'd think that you could ask a user for a text response using input(): name = input(What is your name? ) print Hello, , name But if they just type the answer, Python will crash with an error because it's expecting a legal Python expression there (so a string value would have to be typed in quotes). Remember the cardinal rule NEVER TRUST USER INPUT! Always check for validity, and use methods that prevent malicious strings from allowing the user to get unauthorized access or change things they shouldn't. Many of the common exploits of web pages are the result of poor checking of input resulting in sql injection attacks, and other breaches. Bill ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
Oh, great, this answers my question! Thanks! David [EMAIL PROTECTED] wrote: I am not sure how you got from the input to your variable i, it is a good idea to post your code as well. That said raw_input will return the user's input as a string which you then need to convert to integers. So the commas are brought in as well. You can solve this in a couple of ways: First, you can split the string on the commas and get a list of strings each representing one of the numbers. numberlist=numbers.splt(,) will give you: numberslist=[1,2] which you can then loop over and convert to integers and add up. Secondly, you can have the users input the numbers one at a time inside the loop. add = add + int(raw_input(Please type the next number:)) Chris *David [EMAIL PROTECTED]* Sent by: [EMAIL PROTECTED] 10/02/2008 02:06 PM To tutor@python.org, [EMAIL PROTECTED] cc Subject Re: [Tutor] dealing with user input whose value I don't know Cheers for the insights! However, I just found out that changing input() to raw_input() breaks my code: This program takes the average of numbers you supply!! How many numbers do you want me to work with? 2 You want me to take the average of 2 numbers. Please type the numbers, separated by commas: 1,2 You want to know the average of the numbers: 1,2 Traceback (most recent call last): File avgInput.py, line 13, in module add = add + i TypeError: unsupported operand type(s) for +: 'int' and 'str' End of process output The reason being, I take, that numbers = raw_input(Please type the numbers, separated by commas: ) also returns the comma (1,2) and thus the for loop can't cope... So should I therefore retain numbers = input(Please type the numbers, separated by commas: ) ? Otherwise I don't know (yet) what to do David Bill Campbell wrote: On Thu, Oct 02, 2008, Steve Willoughby wrote: On Fri, Oct 03, 2008 at 01:38:48AM +0800, David wrote: Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? Depends on how you look at it. input() automatically evaluates whatever the user types as a Python expression and returns the result. So if they type 5, the integer 5 is returned. For your program, that's probably what you want, and has the advantage of letting you type something like 2+3 so your user can let Python evaluate math expressions. On the other hand, you'd think that you could ask a user for a text response using input(): name = input(What is your name? ) print Hello, , name But if they just type the answer, Python will crash with an error because it's expecting a legal Python expression there (so a string value would have to be typed in quotes). Remember the cardinal rule NEVER TRUST USER INPUT! Always check for validity, and use methods that prevent malicious strings from allowing the user to get unauthorized access or change things they shouldn't. Many of the common exploits of web pages are the result of poor checking of input resulting in sql injection attacks, and other breaches. Bill ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] dealing with user input whose value I don't know
David [EMAIL PROTECTED] wrote
However, I just found out that changing input() to raw_input()
breaks my code:
You want to know the average of the numbers: 1,2
Traceback (most recent call last):
File avgInput.py, line 13, in module
add = add + i
TypeError: unsupported operand type(s) for +: 'int' and 'str'
End of process output
numbers = raw_input(Please type the numbers, separated by commas:
)
numbers = input(Please type the numbers, separated by commas: ) ?
What is happening is a bit more subtle than you think. I think!...
As others have pointed out input() evaluates whatever the user types
as a python expression. Now a list of numbers separated by commas
is, to python, a tuple. So your input version stores the list of
numbers
as a list(ie. a tuple!) whereas raw_input() stores a string containing
the list of comma separated values.
The solution you have already seen - use string.split(',') to separate
the string into substrings and then convert each substring to an
integer.
As an aside:
What you have done is actually quite a user friendly solution but
I suspect most programmers would have opted to use a loop.
Have you covered loops yet? Specifically a for loop? That would
allow you to read in really long lists of numbers and calculate
the sum as you go.
--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld
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Re: [Tutor] dealing with user input whose value I don't know
David [EMAIL PROTECTED] wrote Does that mean input() is obsolete (after all, Zelle's book is not the freshest on the shelf)? Or do they have different uses? They have different uses and input is very convenient at the prompt or when experimenting but in most cases is the wrong choice for 'production'; code because of its vulnerability to exploitation by crackers and other malicious (or unintentionally malign) users. -- 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
