main.c

int main(int argc, char** argv) {
  char* s;
  char b = '1';
  char a = '2';
  char e = '\0';
  s = &b;
  int i = 0;
  while(*s++ && i++ < 5) {
    *s = '9';
  }
  printf("a: %c e: %c", a, e);
}