C# Program to Check Automorphic Number

Posted in C# Tutorial

Updated on Oct 27, 2024

By Mari Selvan

👁️ 60 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of C# programming, exploring unique number properties is both fascinating and educational. An automorphic number is one such interesting concept.

An automorphic number (or circular number) is a number whose square ends with the number itself. In simpler terms, an n-digit number is called an automorphic number if the last n digits of its square are equal to the number itself.

In this tutorial, we will delve into a C# program that checks whether a given number is an automorphic number or not.

The program will take a number as input, square it, and then compare the last digits to determine if it meets the criteria of an automorphic number.

📄 Example

Let's explore the C# code that accomplishes this task.

Program.cs

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using System;

class Program {
  // Function to check if a number is automorphic
  static bool IsAutomorphic(int num) {
    // Calculate the square of the number
    long square = (long) num * num;

    // Count the number of digits in the original number
    int originalDigits = 0;
    int temp = num;
    while (temp != 0) {
      temp /= 10;
      originalDigits++;
    }

    // Extract the last digits from the square
    long lastDigits = square % (long) Math.Pow(10, originalDigits);

    // Check if the last digits match the original number
    return lastDigits == num;
  }

  // Driver program
  static void Main() {
    // Replace this value with your desired number
    int number = 76;

    // Check if the number is automorphic
    if (IsAutomorphic(number)) {
      Console.WriteLine($"{number} is an automorphic number.");
    } else {
      Console.WriteLine($"{number} is not an automorphic number.");
    }
  }
}

💻 Testing the Program

To test the program with different numbers, simply replace the value of number in the Main method.

Output

76 is an automorphic number.

Compile and run the program to check if the given number is an automorphic number.

🧠 How the Program Works

The program defines a function IsAutomorphic that takes a number as input and returns whether it is an automorphic number or not.
Inside the function, it calculates the square of the input number.
It counts the number of digits in the original number to extract the corresponding number of last digits from the square.
It compares the extracted last digits with the original number to determine if it's an automorphic number.

📏 Between the Given Range

Let's explore the C# code that identifies automorphic numbers in the specified range.

Program.cs

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using System;

class Program {
  // Function to check if a number is automorphic
  static bool IsAutomorphic(int num) {
    int square = num * num;
    while (num > 0) {
      if (num % 10 != square % 10) {
        return false;
      }
      num /= 10;
      square /= 10;
    }
    return true;
  }

  // Driver program
  static void Main() {
    Console.WriteLine("Automorphic numbers in the range 1 to 50:");

    for (int i = 1; i <= 50; i++) {
      if (IsAutomorphic(i)) {
        Console.Write($"{i} ");
      }
    }

    Console.WriteLine();
  }
}

💻 Testing the Program

Output

Automorphic numbers in the range 1 to 50:
1 5 6 25

Run the program to see the automorphic numbers in the range from 1 to 50.

🧠 How the Program Works

The program defines a function IsAutomorphic that takes a number as input and returns true if it is an automorphic number, and false otherwise.
Inside the function, it calculates the square of the number and checks if the last digits match between the number and its square.
The main function iterates through numbers from 1 to 50 and prints the automorphic numbers in that range.

🧐 Understanding the Concept of Automorphic Numbers

Before delving into the code, let's take a moment to understand automorphic numbers.

An n-digit number is called an automorphic number if the last n digits of its square are equal to the number itself.

For example, 25 is an automorphic number because its square is 625, and the last two digits (25) match the original number.

🎢 Optimizing the Program

While the provided program effectively checks for automorphic numbers, you can explore and implement further optimizations or variations based on your specific needs or preferences.

Feel free to incorporate and modify this code as needed for your specific use case. Happy coding!