#include <string.h>

#include <stdio.h>

//#include <stdlib.h>

void foo (char *bar)

{

  unsigned long my_long = 101010101;    // in hex: \xB5\x4A\x05\x06

  char  buffer[28];        

  printf("my_long value = %lu\n", my_long);

  strcpy(buffer, bar);  

  printf("my_long value = %lu\n", my_long);

}

int main (int argc, char **argv)

{

  foo("my string is too long !!!!!");                  // all is normal

  foo("my string is too long !!!!! \x15\xcd\x5b\x07"); // overwrites my_long

  return 0;

}