generic pointer function showing how to cast and call function by it address

pointers.c

#include <stdio.h>

#define FUNC_CAST(retour,function,args...) retour(*function)(args)

typedef FUNC_CAST(void,callback_t,void);
#undef FUNC_CAST
#define FUNC_CAST(retour,function,args...) ((retour(*)(args))function)
int a(int a){
    return printf("%d",a);
}

int b(int a,int b){
    return printf("%u %u",a,b);
}
int main()
{
    
    callback_t p;
    printf("%d %d\n",sizeof(callback_t),sizeof(short));
    p=(void(*)(void))a;
    ((int(*)(int))p)(53);
    putchar('\n');
    p=(void(*)(void))b;
    ((int(*)(int))p)(0b11111111111111111111111111111111);
     putchar('\n');
    ((int(*)(int,int))p)(11,12);
    putchar('\n');
    (*FUNC_CAST(int,&b,int,int))(13,14);
    putchar('\n');
    FUNC_CAST(int,p,int,int)(15,16);

    return 0;
}