Question

Getting back in to some C work.

Many of my functions look like this:

int err = do_something(arg1, arg2, arg3, &result);

With the intent the result gets populated by the function, and the return value is the status of the call.

The darkside is you get something naive like this:

int err = func1(...);
if (!err) {
    err = func2(...);
    if (!err) {
        err = func3(...);
    }
}
return err;

I could macro it I suppose:

#define ERR(x) if (!err) { err = (x) }
int err = 0;
ERR(func1(...));
ERR(func2(...));
ERR(func3(...));
return err;

But that only works if I’m chaining function calls, vs doing other work.

Obviously Java, C#, C++ have exceptions that work very well for these kinds of things.

I’m just curious what other folks do and how other folks do error handling in their C programs nowadays.

Answer 1

Two typical patterns:

int major_func()
{
    int err = 0;

    if (err = minor_func1()) return err;
    if (err = minor_func2()) return err;
    if (err = minor_func3()) return err;

    return 0;
}

int other_idea()
{
    int err = minor_func1();
    if (!err)
        err = minor_func2();
    if (!err)
        err = minor_func3();
    return err;            
}

void main_func()
{
    int err = major_func();
    if (err)
    {
        show_err();
        return;
    }
    happy_happy_joy_joy();

    err = other_idea();
    if (err)
    {
        show_err();
        return;
    }
    happy_happy_joy_joy();
}