#include <stdio.h>

void wissel(int *p, int *q) {
    int hulpje = *p;
    *p = *q;
    *q = hulpje;
}

int main(void) {
    int x = 7, y = 8;
    printf("x = %d en y = %d\n", x, y);
    wissel(&x, &y);
    printf("x = %d en y = %d\n", x, y);
    getchar();
    return 0;
}