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 Does that mean input() is obsolete (after all, Zelle's book is not the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