# C++ Program to Swap Two Numbers

There are two ways to create a program to swap two numbers. One involves using a temp variable and the second way does not use a third variable. These are explained in detail as follows −

## Program to Swap Two Numbers using temp Variable

The program to swap two numbers using a temp variable is as follows.

## Example

Live Demo

#include <iostream >
using namespace std;
int main() {
int a = 10, b = 5, temp;
temp = a;
a = b;
b = temp;
cout<<"Value of a is "<<a<<endl;
cout<<"Value of b is "<<b;
return 0;
}

## Output

Value of a is 5
Value of b is 10

In the above program, there are two variables a and b that store the two numbers. First, the value of a is stored in temp. Then, the value of b is stored in a. Lastly, the value of temp is stored in b. After this, the values in a and b are swapped.

temp = a;
a = b;
b = temp;

Then the values of a and b are displayed.

cout<<"Value of a is "<<a<<endl;
cout<<"Value of b is "<<b;

## Program to Swap Two Numbers Without Using a Third Variable

The program to swap two numbers without using a third variable is as follows −

## Example

Live Demo

#include <iostream>
using namespace std;
int main() {
int a = 10, b = 5;
a = a+b;
b = a-b;
a = a-b;
cout<<"Value of a is "<<a<<endl;
cout<<"Value of b is "<<b;
return 0;
}

## Output

Value of a is 5
Value of b is 10

In the above program, first the sum of a and b is stored in a. Then, the difference of a and b is stored in b. Finally, the difference of a and b is stored in b. At the end of this, the values in a and b are swapped.

a = a+b;
b = a-b;
a = a-b;

Then the values of a and b are displayed.

cout<<"Value of a is "<<a<<endl;
cout<<"Value of b is "<<b;

Updated on: 24-Jun-2020

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