Return Values

**Drahcir** · 03-20-2006

I'm really sorry if this is a dumb question but ever since I started using C, I never understood the reason why functions are defined with much larger values then required.

I'm planning to write an commercial API so I wish to get my code written as best as possible, so I won't have to go back and fix things later.

My questions is that they're are millions of functions out there but many are definied with much higher variables then required.

An example of this is the int SDL_Flip(SDL_Surface *screen); function in the Simple Direct Layer library. The function will only return two possible values, 0 for success & -1 on an error. So why is this defined as an interger? Wouldn't be better to define this as an char?

int main(int argc, char *argv[]) is another one. I'll be very surpised if their was a single program that could return 4228250625 different return values with good reason. I'm sure most people just use two. One for a success and another for an error. I'm guessing that main() is an expection however, because it's not like any other function.

So why are some many programs and functions like this? I'm sure that changing these won't ever gain the slightest speedup, but this wouldn't this make your executables a few bytes smaller?

Thanks to any replies. Once again sorry if this was a stupid question.

**sand_man** · 03-20-2006

If you are trying to save space then I guess so. But at a higher level point of view, you know you are checking for a number/integer not an actual character.

There are some other exceptions like getchar() returns an int because some values are in fact larger than a char.

**Salem** · 03-20-2006

> Wouldn't be better to define this as an char?
Historically, all C functions returned int by default, unless you went out of your way to indicate that it returned something else.

Also return values in particular are returned in machine registers, so it makes sense to use a type which is closest to the machine, and traditionally int served this role.

The char type may be signed or unsigned, so it does not make sense to try and return a negative value since that would break on machines which default to char as being unsigned.

> I'm planning to write an commercial API so I wish to get my code written as best as possible
You could consider making all your return types as enumerations.

**fgw_three** · 03-20-2006

And something else you might want to consider....

If it is commercial, at some point it will probably have to be maintained by someone else. While trying to keep it as small as possible is a laudable goal, if you get too far from the "norm", you might pay a price later on if someone other programmer needs to come up to speed and maintain it.

**cwr** · 03-21-2006

Originally Posted by Drahcir

I'm sure that changing these won't ever gain the slightest speedup, but this wouldn't this make your executables a few bytes smaller?

As Salem said, int tends to be the size of a register on a given machine, so using char instead of int for function return values may actually increase the size of the executable, since you need extra instructions to convert.

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