//Unsafe code example
// run with vagrind -q a.out
#include <iostream>
#include <vector>
int main(void)
{
  std::vector<int> v(1);
  int& r = v[0];
  r = 1; // ok, the reference is valid
  std::cout<<"v[0]="<<v[0]<<" r="<<r<<"\n";
  v.resize(100); // try here 10 or 100 or bigger
  r = 2; // segfault or not !
  std::cout<<"v[0]="<<v[0]<<" r="<<r<<"\n";
}