#include <stdlib.h>
#include <stdio.h>

int f(char *tab){

    int x = 0x1234;
    *tab = 0x1234;

    if (tab[0] == 0x34){
        tab[1] = 2;
    }

    if (tab[1] == 0x02){
        tab[1] = 1;
    }

    if (tab[3] == 0x04){
        return 5;
    }

    return 0;
}


int main(void){

char tab[]={0x01,0x02,0x03,0x04};

*(tab + 3) = f(tab);

return 0;
}