#include <iostream>

using namespace std;

void counter(int increment)
{ // int total;
  //   does not work, just an uninitialised variable
  // int total = 0;
  //   also no good, total re-zeroed every time
  static int total = 0;
  //   just the trick
  total += increment;
  cout << "  counter(" << increment << "): total is now " << total << "\n"; }

int main()
{ cout << "calling counter(1)\n";
  counter(1);
  cout << "calling counter(3)\n";
  counter(3);
  cout << "calling counter(2)\n";
  counter(2);
  cout << "calling counter(1)\n";
  counter(1);
  cout << "calling counter(10)\n";
  counter(10);
  cout << "calling counter(1)\n";
  counter(1);
  cout << "calling counter(2)\n";
  counter(2); }