This program asks user to enter two integers and displays all Armstrong numbers between the given interval.

If you don't know how to check whether a number is Armstrong or not in programming then, this program may seem little complex.

Visit this page to learn about Armstrong number and how to check it in C++ programming.

## Example: Display Armstrong Number Between Intervals

```
#include <iostream>
using namespace std;
int main()
{
int num1, num2, i, num, digit, sum;
cout << "Enter first number: ";
cin >> num1;
cout << "Enter second number: ";
cin >> num2;
cout << "Armstrong numbers between " << num1 << " and " << num2 << " are: " << endl;
for(i = num1; i <= num2; i++)
{
sum = 0;
num = i;
for(; num > 0; num /= 10)
{
digit = num % 10;
sum = sum + digit * digit * digit;
}
if(sum == i)
{
cout << i << endl;
}
}
return 0;
}
```

**Output**

Enter first number: 100 Enter second number: 400 Armstrong numbers between 100 and 400 are: 153 370 371

In this program, it is assumed that, the user always enters smaller number first.

This program will not perform the task intended if user enters larger number first.

You can add the code to swap two numbers entered by user if user enters larger number first to make this program work properly.

In this program, each number between the interval is taken and stored in variable `num`. Then, each digit of the number is retrieved in `digit` and cubed (^3).

The cubed result is added to the cubed result of the last digit `sum`.

Finally, when each digit is traversed, `sum` is compared with the original number `i`. If they are equal, the number is an armstrong number.