return statement

[vatos]

Hello..


Sorry if this sounds a bit dumb but can somebody explain to me what the return statement means? I'm getting confused with all the diff types i see. I'm still new to this by the way.

eg

return 0;
retrurn EXIT_SUCCESS;
return EXIT_FAILURE;
return 1;
return ;

oh...and also EXIT (0); ??

thanx a lot.

[master5001]

Okay, well this is pretty simple. First off let me address the EXIT_SUCCESS/EXIT_FAILURE thing. In stdlib.h you will find macros that define these as 0 and 1, respectively. In other words:

return 0;

// and

return EXIT_SUCCESS;

Mean the same thing. The exit() function is the standard c way of stopping execution of your program. A return itself is the value that a function returns.

Example

int func1(void) {
  return 0;
}

float func2(void) {
  return 81.33;
}

char *func3(void) {
  return malloc(32);
}

[Cela]

>>In stdlib.h you will find macros that define these as 0 and 1, respectively.
Maybe, but you can't be sure that the literals behind the macros are 0 and 1 and relying on that means you lose portability.

>>return malloc(32);
And if malloc fails? :-)

[quzah]

Originally posted by Cela
>>return malloc(32);
And if malloc fails? :-)

Then it simply returns what malloc returns on failure. NULL. Not a difficult concept.

Quzah.

[Cela]

>>Not a difficult concept.
Except that the most common use for a function that returns a block of memory is to assume it's valid and use it immediately. Even most of the calls to malloc I've seen assume everything is kosher. So it's better to protect obviously less than stellar programmers against themselves because they might be working next to you :-)

[Hammer]

>>Except that the most common use for a function that returns a block of memory is to assume it's valid and use it immediately
Not in my experience. That philosphy doesn't exist in any of the code I write/maintain.

>>So it's better to protect obviously less than stellar programmers against themselves
Which is why you should always use well written comments in your code. Returning NULL from a function because something failed is common practice, and is easy to understand, especially if it is documented at the top of the function.

Using the malloc example, remember that if malloc fails in "your" function, it doesn't mean the caller wants to be restricted to your error handling.

[Cela]

Well, I've been suitably chided in this thread, my work here is done :-)

[vatos]

thanx guys...


and what about this?

return ( (b1 < b2) ? b1 : b2 );

[Polymorphic OOP]

Originally posted by vatos
thanx guys...


and what about this?

return ( (b1 < b2) ? b1 : b2 );

if b1 is less than b2 it returns b1 or else it returns b2.