Pass by reference by using pointer : reference parameter « Function « C++ Tutorial

1. C++ Tutorial
2. Function
3. reference parameter

#include <iostream>
 
 void swap(int *x, int *y);
 
 int main()
 {
     int x = 5, y = 10;
 
     std::cout << "Main. Before swap, x: " << x << " y: " << y << "\n";
     swap(&x,&y);
     std::cout << "Main. After swap, x: " << x << " y: " << y << "\n";
     return 0;
 }
 
 void swap (int *px, int *py)
 {
     int temp;
 
     std::cout << "Swap. Before swap, *px: " << *px << " *py: " << *py << "\n";

 
     temp = *px;
     *px = *py;
     *py = temp;
 
     std::cout << "Swap. After swap, *px: " << *px << " *py: " << *py << "\n";

 }

Main. Before swap, x: 5 y: 10
Swap. Before swap, *px: 5 *py: 10
Swap. After swap, *px: 10 *py: 5
Main. After swap, x: 10 y: 5