#include <stdio.h>                                 /* strings.c */

char a[] = "Hello world!";
char * p = a;
char * s = "Hello world!";          /*@{}@XPC{@B{Read-only data!} (on some systems)} */

int main () {
  a[5] = '~';

  printf("p = %s\n", p);
  p[5] = '_';
  printf("p = %s\n", p);

  printf("s = %s\n", s);
  s[5] = '_';                            /*@{}@XPC{@B{segmentation fault!}} */
  printf("s = %s\n", s);

  return 0;
}