在IDLE中出现NameError问题-Python

Question

got some trouble with my selfmade code.

def even(a, b):
    f = []
    while a <= b:
        if a % 2 == 0:
            f.append(a)
        a = a + 1
    return f;

When i'm tryin to call it from the shell it says:

Traceback (most recent call last):
File "<pyshell#43>", line 1, in <module>
even(0,200)
NameError: name 'even' is not defined.

I think it's not a really tricky problem, but can u help my anyway? Thank you up front. Cheers

Answer 1

Two things. Are you indenting your function correctly and how are you calling your function? the following code works:

def even(a, b):
    f = []
    while a <= b:
        if a % 2 == 0:
            f.append(a)
        a = a + 1
    return f;

print(even(2,3))
#output: [2]

Notice the indentation and the fact that even is being called after it is defined.

Edit: I notice you've gotten it working, now would be a good time to refacter some parts of your function ie give the variable fa more descriptive name.

Answer 2

If you want to run it from your shell, you would want to:

1. enter python into shell, to start your python interpreter
2. enter from <your-code's-filename.py> import even

then you can use the function as you tried: even(0,200)

But you can also just run it from within IDLE like Wright suggests.