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Does that mean input() is obsolete (after all, Zelle's book is not the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
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