15callbyref.cpp

#include<iostream>
using namespace std;

void swap(int a, int b) // this method would not work as the variables changing here doesn't affect the actual parameters
{
    int temp = a;
    a = b;
    b = temp;
}
void swapWithPointer(int *a, int *b) //this will work as it takes the address of actual parameters
{
    int temp = *a;
    *a = *b;
    *b = temp;
}
void swapWithReferenceVar(int &a, int &b) //using reference variable where 2 variables point to a single value simultaneously
{
   int temp = a; //no dereferencing
    a = b;
    b = temp; 
}
int main()
{
    int x = 4, y = 6;
    cout<<"The value of x before swap is "<<x<<" and of y is "<<y<<endl;
    swap(x, y); //this method won't work
    swapWithPointer(&x, &y); // this will work as the address is passed to the formal parameters
    cout<<"The value of x after swap is "<<x<<" and of y is "<<y<<endl;
    int i = 3, j = 5;
    cout<<"The value of i before swap is "<<i<<" and of j is "<<j<<endl;
    swapWithReferenceVar(i, j); //no address
    cout<<"The value of i after swap is "<<i<<" and of j is "<<j<<endl;
    
    return 0;
}