C++通过引用调用

#include <iostream>

using namespace std;

// function deFinition to swap the values.
void swap(int &x, int &y) {
   int temp;
   temp = x;   /* save the value at address x */
   x = y;      /* put y into x */
   y = temp;   /* put x into y */

   return;
}

// function declaration
void swap(int &x, int &y);

int main () {
   // local variable declaration:
   int a = 100;
   int b = 200;

   cout << Before swap, value of a : << a << endl;
   cout << Before swap, value of b : << b << endl;

   /* calling a function to swap the values using variable reference.*/
   swap(a, b);

   cout << After swap, value of a : << a << endl;
   cout << After swap, value of b : << b << endl;

   return 0;
}