C++ Exercises: Find the Armstrong number for a given range of number

Last update on April 12 2025 13:00:27 (UTC/GMT +8 hours)

44. Find Armstrong Numbers in a Given Range

Write a C++ program to find the Armstrong number for a given range of numbers.

/*When the sum of the cube of the individual digits of a number
is equal to that number, the number is called Armstrong number. For example 153.
Sum of its divisor is 13 + 53;+ 33; = 1+125+27 = 153*/

Sample Solution:

C++ Code:

#include <iostream>
#include <math.h>
using namespace std;

int main()
{
    // Initialize variables
    int num, r, sum, t, mm;
    int sno, eno;

    // Display instructions to the user
    cout << "\n\n Find the Armstrong number for a given range of number:\n";
    cout << "-----------------------------------------------------------\n";

    // Input starting and ending numbers for the range
    cout << " Input starting number of range: ";
    cin >> sno;
    cout << " Input ending number of range: ";
    cin >> eno;

    // Display a message for Armstrong numbers found in the range
    cout << " Armstrong numbers in given range are: " << endl;

    // Loop through the range of numbers to find Armstrong numbers
    for (num = sno; num <= eno; num++) 
    {
        t = num; // Store the current number in a temporary variable
        sum = 0; // Initialize the sum variable to zero

        // Calculate the sum of cubes of digits in the number
        while (t != 0) 
        {
            r = t % 10; // Extract the last digit
            mm = pow(r, 3); // Calculate the cube of the digit
            sum = sum + mm; // Add the cube to the sum
            t = t / 10; // Remove the last digit
        }

        // Check if the sum of cubes of digits equals the original number
        if (sum == num)
            cout << num << " "; // Print the Armstrong number found
    }
    cout << endl;
}

Sample Output:

 Find the Armstrong number for a given range of number:                
-----------------------------------------------------------            
 Input starting number of range: 25                                    
 Input ending number of range: 200                                     
 Armstrong numbers in given range are:                                 
153

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to list all Armstrong numbers within a specified range using iterative digit processing.
Write a C++ program to generate Armstrong numbers in a range by leveraging vector storage and STL algorithms.
Write a C++ program to compute Armstrong numbers between two limits with optimized power functions for each digit.
Write a C++ program to display Armstrong numbers in a range along with their corresponding digit power sums.

C++ Code Editor:

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