// Program to demonstrate 
//Null-Pointer Dereferencation
int main(int argc, char ** argv){
  char buf[255];
  char * ptr = NULL;
  if (argc>1) {
    ptr = argv[1];
  }
  strcpy(str,ptr);
  return 0;
}

Output :
Runtime Error : Segmentation Fault (SIGSEGV)