Default parameters

#include <iostream>
using namespace std;
int add (int a, int b = 2)
{
  return a + b; 
}

int main ()
{
  int x=1;
  int result; 
  result = add (x);
  cout << " sum " << result << "\n";
  result = add (x, 10);
  cout << " sum " << result << "\n";
}