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# C++ Program To Swap Two Numbers Using Functions

In this tutorial, we need to write a Program for Swapping Two Numbers in C++ Using Call By Value and Call by Reference. There are two methods to solve this problem with the help of functions, and there are two methods to do this the first is Call By Value and Call by Reference. Now let's discuss the Call by Value in detail. In the function we can pass the value in 2 ways the first one is Call By Value and the second one is called by Reference there are 2 things we have to discuss Actual Parameter and Formal Parameter to fully understand the passing values in the function in C++ Programming language. In this article I am going to tell you the Call By Value, Call by Reference, Actual Parameter, and Formal Parameter to fully understand the programming problem.

## Program To Swap Two Numbers Using Functions In C++

### 1. Call by Value

In Call by Value Actual parameters are passed while calling the function, The operations effect on the formal parameters doesn't reflect on the Actual Parameters.

Example: Int A = 5 is an actual parameter and Int X = 5(Here we have Copied the Int A = 5 value to the X = 5), so whatever we do with the X, it does not reflect the Actual Value Int A = 5. It will always remain the same. If we increase the value of the X by 1 then the value of the X will be 6 and the value of the A remains the same 5 as previous.

``````#include<iostream>
using namespace std;

void swap(int ,int );
/*Swapping of Two Numbers in C++ Using Functions Call by Value*/
int main()
{

int a,b;
cout<<"Enter the Two Numbers to Swap in C++: ";
cin>>a>>b;
cout<<"\nAfter Swapping of Two Numbers:";
swap(a,b);

return 0;
}
void swap(int x,int y)
{
int z;
/*Extra veriable for storing the value of first or second variable*/

z=x;
/*Copying the first variable value to the tempriory variable*/
x=y;
/*Copying the second variable value to the first variable*/
y=z;
/*Copying the tempriory variable value to the second variable*/
cout<<" "<<x<<"   "<<y;

}``````

Enter the Two Numbers to Swap in C++: 8 6

After Swapping of Two Numbers: 6 8

### 2. Call by Reference

In Call by Reference we passed the address of the actual parameter in a formal parameter, So the changes on the Formal Parameters reflect on the Actual parameters. If we take the above example for this then if we increase the value of the X will reflect on the A thus the value of the X and A will be the same(X = A = 6)

Before going to understand the Call by value and Call by Reference let's first understand the Actual and Formal Parameters terminology to fully understand the code.

Actual parameters: The Actual parameters that appear in function calls.

Formal parameters: The Formal parameters that appear in function declarations.

``````#include<iostream>
using namespace std;

void swap(int *x ,int *y );
/*Swapping of Two Numbers in C++ Using Functions Call by Reference*/
int main()
{

int a,b;
cout<<"Enter Two Numbers To Swap: ";
cin>>a>>b;

swap(&a,&b);

cout<<"\nAfter Swapping Two Numbers: ";
cout<<a<<" "<<b<<" \n";

return 0;
}
void swap(int *x,int *y)
{
int z;
z=*x;
/*Copying the first variable Address to the temporary variable*/
*x=*y;
/*Copying the second variable Address to the first variable*/
*y=z;
/*Copying the temporary variable Address to the second variable*/
}``````

Enter Two Numbers To Swap: 4 56

After Swapping Two Numbers: 56 4

## Conclusion

Here, in this tutorial, we have learned how to use functions to swap two numbers given by the user.