C++ Program to Reverse a Number

In this post, we will learn how to reverse a number using C++ Programming language.

This program asks the user to enter an integer, then it reverse the integer using a while loop.

So, without further ado, letâ€™s begin this tutorial.

C++ Program to Reverse a Number

```// C++ Program to Reverse a Number
#include <iostream>
using namespace std;

int main(){
int n, rem, reverse_number = 0;

cout << "Enter an integer: ";
cin >> n;

// Reversing the number
while (n != 0){
rem = n % 10;
reverse_number = reverse_number * 10 + rem;
n = n / 10;
}

// Displaying output
cout << "Reversed Number: " << reverse_number << endl;
return 0;
}
```

Output

``````Enter an integer: 746
Reversed Number: 647
``````

How Does This Program Work ?

```    int n, rem, reverse_number = 0;
```

In this program, we have declared three integer data type variables named n, rem and reverse_number. reverse_number variable has assigned a value of 0.

```    // Asking for input
cout << "Enter an integer: ";
cin >> n;
```

The user is asked to enter a number which he wants to reverse. This value gets stored in the ‘n‘ named variable.

```    // Reversing the number
while (n != 0){
rem = n % 10;
reverse_number = reverse_number * 10 + rem;
n = n / 10;
}
```

The entered integer gets reversed using a while loop. Suppose, the user enters an integer 746.

• 1st While Loop Iteration: while (746 != 0), here the condition is True, so the loop continues.
• rem = n % 10 = 746 % 10 = 6
• reverse_number = reverse_number * 10 + rem = 0 * 10 + 6 = 0 + 6 = 6
• n = n / 10 = 746 / 10 = 74

Now, n becomes 74 and reverse_number becomes 6.

• 2nd While Loop Iteration: while (74 != 0), here the condition is also True, so the loop continues.
• rem = n % 10 = 74 % 10 = 4
• reverse_number = reverse_number * 10 + rem = 6 * 10 + 4 = 60 + 4 = 64
• n = n / 10 = 74 / 10 = 7

Now, the value of n becomes 7 and reverse_number becomes 64.

• 3rd While Loop Iteration: while (7 != 0), here the condition is True, so the loop continues.
• rem = n % 10 = 7 % 10 = 7
• reverse_number = reverse_number * 10 + rem = 64 * 10 + 7 = 640 + 7 = 647
• n = n / 10 = 7 / 10 = 0

Now, the value of n becomes 0 and reverse_number becomes 647.

• 4th While Loop Iteration: while (0 != 0), here the condition is False, so the loop terminates and we get reverse_number = 647 which is the reverse of the original number.
```    // Displaying output
cout << "Reversed Number: " << reverse_number << endl;
```

Then, the reversed number of the entered integer is displayed on the screen using the cout statement.

Conclusion

I hope after going through this post, you understand how to reverse a number using C++ Programming language.

If you have any doubt regarding the program, then contact us in the comment section. We will be delighted to assist you.