C Callbacks

function_pointer.c

#include <stdio.h>

// The original function (adds two number and sets
// the results into the first one
void add(int *x, int *y)
{
    *x = *x + *y; 
}

void sub(int *x, int *y)
{
    *x = *x - *y;
}

// Runs the callback given some parameters. Can also be thinked
// as a "decorator".
//
// TODO: Find a way to pass cb's arguments without polluting
// the main function.
void call_callback(int *a, int *b, void (*cb)(int *, int *))
{
    (*cb)(a, b);
}

int main(int argc, const char *argv[])
{
    int a = 2;
    int b = 3;

    printf("%d + %d = ", a, b);
    call_callback(&a, &b, add);
    printf("%d\n", a);

    printf("%d - %d = ", a, b);
    call_callback(&a, &b, sub);
    printf("%d\n", a);

    return 0;
}