C++ Exercises: Generate and show all Kaprekar numbers less than 1000

Last update on April 12 2025 13:00:04 (UTC/GMT +8 hours)

10. Show All Kaprekar Numbers Less Than 1000

Write a program in C++ to generate and show all Kaprekar numbers less than 1000.

Visual Presentation:

C++ Exercises: Generate and show all Kaprekar numbers less than 1000

Sample Solution:

C++ Code :

#include<bits/stdc++.h> // Include the entire standard C++ library
using namespace std;

bool chkkaprekar(int n)
{
    if (n == 1)
        return true; // If the number is 1, it's considered a Kaprekar number

    int sqr_n = n * n; // Calculate the square of the number
    int ctr_digits = 0; // Variable to count the number of digits in the square

    // Calculate the number of digits in the square of n
    while (sqr_n)
    {
        ctr_digits++; // Increment the digit count
        sqr_n /= 10; // Reduce the number by one digit
    }

    sqr_n = n * n; // Reset sqr_n to n squared
    for (int r_digits = 1; r_digits < ctr_digits; r_digits++)
    {
        int eq_parts = pow(10, r_digits); // Determine the equal parts for the comparison

        if (eq_parts == n)
            continue; // If equal parts match the number, skip the comparison

        // Calculate the sum of two parts after splitting the square number
        int sum = sqr_n / eq_parts + sqr_n % eq_parts;

        if (sum == n)
            return true; // If the sum matches the original number, it's a Kaprekar number
    }
    return false; // If no condition satisfies, it's not a Kaprekar number
}

int main()
{
    cout << "\n\n Generate and show all Kaprekar numbers less than 1000: \n"; // Display a message for user
    cout << " -----------------------------------------------------------\n";
    cout << " The Kaprekar numbers less than 1000 are: " << endl;

    // Check for Kaprekar numbers in the range from 1 to 999 and display them
    for (int i = 1; i < 1000; i++)
    {
        if (chkkaprekar(i))
        {
            cout << i << " "; // Print the Kaprekar number
        }
    }
    cout << endl;
    return 0; // End of the program
}

Sample Output:

 Generate and show all Kaprekar numbers less than 1000:                
 -----------------------------------------------------------           
 The Kaprekar numbers less than 1000 are:                              
1 9 45 55 99 297 703 999

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to list all Kaprekar numbers below 1000 using a for-loop with efficient digit splitting.
Write a C++ program to generate Kaprekar numbers under 1000 while optimizing performance with early termination.
Write a C++ program to display all Kaprekar numbers below 1000 using vector storage and STL iterators.
Write a C++ program to list Kaprekar numbers under 1000 using lambda expressions for clarity and brevity.

C++ Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a program in C++ to check whether a given number is a Kaprekar number or not.
Next: Write a program in C++ to check whether a number is Lychrel number or not.