Can you run a function on initialization in c?

Question

Is there an mechanism or trick to run a function when a program loads?

What I\'m trying to achieve...

void foo(void)
{
}

register_function(foo);
<         


        

Answer 1

There is no standard way of doing this although gcc provides a constructor attribute for functions.

The usual way of ensuring some pre-setup has been done (other than a simple variable initialization to a compile time value) is to make sure that all functions requiring that pre-setup. In other words, something like:

static int initialized = 0;
static int x;

int returnX (void) {
    if (!initialized) {
        x = complicatedFunction();
        initialized = 1;
    }
    return x;
}

This is best done in a separate library since it insulates you from the implementation.