Call by value, Call by Reference, Returning Values from a Function

Arguments Passing Techniques
C++ is the mother of Object-Oriented Programming.

Arguments Passing is a Process of transferring data between the calling function and the called function. In C++,  there are three ways by which arguments can be passed.

1. Pass By Value
2. Pass By Address or Pass By Pointer
3. Pass By Reference

Video Explanation: C++ Program to swap two numbers with the third variable.   https://youtu.be/pq9VWQswqwo

Video: Call By Value

Most of the programming languages like C use only the first two modules (i.e., Passing by Value and Address) whereas C++ supports all the three methods of passing arguments.

Pass By Value: It is a default method for argument passing. When an argument is passed by value than a copy of the argument is made and passed to the newly created formal arguments in the called function. The formal arguments contain a copy of actual arguments which is stored in the separate memory location.  

Program to Show How Pass By Value Works. C++ Program to swap two numbers with the third variable.

PROGRAM OUTPUT: -

Pass By Reference:
The Pass by reference is the very easy and simple technique of argument passing which is only available in C++(not in C). This technique allows modifications back to the actual arguments.

OUTPUT: 

Explanation: The above program shows swapping of 2 numbers using pass by reference. When the function swap(a,b); is called, the actual arguments a and b are passed by reference. 

In the function definition, the formal arguments x and y are reference variables of the corresponding actual arguments a and b respectively.