Call by reference in cpp is one approach to implement function ( to call function)
In this tutorial we will see what is function, call by reference and program for call by reference.
What is function : function is block of code.
Call by reference: When function are called by passing the address they are called as call by reference. its alse called as call by address in c++.
What is reference variable : It is one of the analysis all the other names given to the memory location. In short reference are the multiple names given to the same memory locations.
Call by reference example

C++ function call by reference
Call by reference program in c++
12345678910111213141516171819202122232425262728 | #include <iostream>using namespace std;void swap(int *x ,int *y );//Call By refernceint main(){ int a,b; cout<<“\nEnter Two Number To Swap :\n”; cin>>a>>b;cout<<“\n Before Numbers :\n\n”; cout<<“x= “<<a<<” “<<“y= “<<b<<” \n”; cout<<“\nAfter Swapping Numbers :\n\n”; swap(&a,&b); cout<<“x= “<<a<<” “<<“y= “<<b<<” \n”; return 0;}void swap(int *x,int *y){ int z; z=*x; *x=*y; *y=z; } |
Output :

Explanation :
1. First we declare the function which is swap function
=> void swap(int *x ,int *y);
2. Execution starts with the main method.
3. Declare the variables
a, b => to store two numbers
4. Take a input from user two numbers
=> cin>>a>>b; a = 10, b= 20
5. We print numbers before swapping.
6. Next we call function by passing address of a and b
swap(&a,&b); => function get executed
swap(int *x,int *y) { => x= 10 y = 20
*z=*x; => *z=10
*x=*y; => *x=20
*y=*z; =>*y = 10
} => Returns to main function
7. Now we print numbers after swapping
cout<<“x= “<<x<<” “<<“y= “<<y<<” \n”;
8. End with the program.