#include <stdio.h>

int main(void)
{
    char s[20] = "abcdef";
    char q[20];

    char *p;
    char *r;

    p = s;
    r = q;

    printf("%s\n", s);
    printf("%s\n", q);

    while( (*r++ = *p++) );

    printf("%s\n", s);
    printf("%s\n", q);

    return 0;
}