#include <stdio.h>

// prohozeni dvou hodnot
void swap(int *a, int *b) {
    int tmp = *a;
    *a = *b;
    *b = tmp;
}

int main() {

    int a = 4;
    int b = 2;

    printf("a = %d, b = %d\n", a, b);

    swap(&a, &b);

    printf("a = %d, b = %d\n", a, b);

    return 0;
}