[prog] quick question on Python

[Mary]

On Sun, Dec 08, 2002, Guru - wrote:
> Regrading this function:
> def euclid(a,b):
>        while b:
>        a,b = b,a % b
>        print "Common factor is", a
>        return a


Wouldn't the syntax have to be:

def euclid(a,b):
        while b:
                a,b = b,a % b
                print "Common factor is", a
        return a

?

> With the return a....I'm confused on what exactly it does.  Becuase if
> I said print (after using the function) "This is the answer", a.  a
> wouldn't be the variable that was found inside the function.  So what
> exactly does the return do, besides end the function?

The return value can be assigned to something outside a function.

For example,

I could simply write a piece of code that called your method:

euclid(6, 3)

which will make no use of the return value.

Or, since euclid returns a value, I can assign a variable to that value:

b = euclid(6, 3) # b is now the value that was returned, that is:
                 # b is equal to euclid's a variable

Or I could print it:

print "the greatest common divisor of %d and %d is %d\n" % (6, 3, euclid(6, 3))

That is, because euclid returns a value, I can treat a call to euclid
like it is a variable.

-Mary