swap

#include <stdio.h>

void putint(int a)
{
    printf("%i", a);
}

int main()
{
    int a;
    int b;
    a = 10;
    b = 20;
    int *pttoa;
    pttoa = &a;
    int *pttob;
    pttob = &b;

    int tmp;
    tmp = *pttoa;
    a = b;
    b = tmp;



    putint(a);
    putint(b);

    return 0;
}