#include <iostream>
 
using namespace std;
 
// this function increments the actual variable
// passed as an argument because it is passed
// as reference (with & in front of its name)
 
void correct_increment(int &i)
{
  i++;
}
 
// this function does increment only a copy
// of the input argument, so the modifications
// are lost once the function terminates
 
void wrong_increment(int i)
{
  i++;
}
 
// main function
 
int main()
{
  int i=0;
 
  // call wrong increment 3 times
 
  wrong_increment(i);
  wrong_increment(i);
  wrong_increment(i);
 
  // print out the result
 
  cout << "value of i after 3 calls to wrong_increment: " << i << endl;
  cout << endl;
 
  // call wrong increment 3 times
 
  correct_increment(i);
  correct_increment(i);
  correct_increment(i);
 
  // print out the result
 
  cout << "value of i after 3 calls to correct_increment: " << i << endl;
 
  // return 0 from the main
 
  return 0;
}

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