C# Program to find Composite Number

Posted in C# Tutorial

Updated on Jan 11, 2024

By Mari Selvan

👁️ 113 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, identifying and working with different types of numbers is a fundamental skill.

A composite number is one that has more than two positive divisors, excluding 1 and itself. In this tutorial, we'll explore a C# program that efficiently determines whether a given number is composite or not.

📄 Example

Let's dive into the C# code that checks whether a number is composite or not.

Program.cs

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using System;

class Program {
  // Function to check if a number is composite
  static bool IsComposite(int number) {
    if (number <= 1)
      return false;

    for (int i = 2; i <= Math.Sqrt(number); i++) {
      if (number % i == 0)
        return true;
    }

    return false;
  }

  // Driver program
  static void Main() {
    // Replace this value with your desired number
    int testNumber = 12;

    // Check if the number is composite
    if (IsComposite(testNumber))
      Console.WriteLine($"{testNumber} is a composite number.");
    else
      Console.WriteLine($"{testNumber} is not a composite number.");
  }
}

💻 Testing the Program

To test the program with a different number, replace the value of testNumber in the Main function.

Output

12 is a composite number.

Compile and run the program to see if the given number is composite.

🧠 How the Program Works

The program defines a function IsComposite that takes an integer as input and returns true if the number is composite, and false otherwise.
Inside the function, it checks if the given number is less than or equal to 1. If so, it returns false since 1 and numbers less than 1 are not composite.
It then iterates from 2 to the square root of the given number and checks if any of these values evenly divide the number. If so, the number is composite.
The Main function tests the program by providing a test number and prints whether it is composite or not.

📏 Between the Given Range

Let's delve into the C# code that checks for composite numbers in the range of 1 to 10.

Program.cs

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using System;

class Program {
  // Function to check if a number is composite
  static bool IsComposite(int number) {
    if (number < 2)
      return false;

    for (int i = 2; i < number; i++) {
      if (number % i == 0)
        return true;
    }

    return false;
  }

  // Driver program
  static void Main() {
    Console.WriteLine("Composite numbers in the range 1 to 10:");

    // Check numbers from 1 to 10
    for (int i = 1; i <= 10; i++) {
      if (IsComposite(i))
        Console.Write($"{i} ");
    }

    Console.WriteLine();
  }
}

💻 Testing the Program

Output

Composite numbers in the range 1 to 10 are: 
4 6 8 9 10

The program is designed to check and display composite numbers in the range of 1 to 10. Run the program, and it will output the composite numbers in that range.

🧠 How the Program Works

The program defines a function IsComposite that takes a number as input and returns true if the number is composite, and false otherwise.
Inside the function, it checks if the number has any divisors other than 1 and itself.
The Main method then checks and prints the composite numbers in the range of 1 to 10 using a for loop.

🧐 Understanding the Concept of Composite Numbers

Composite numbers are integers greater than 1 that have divisors other than 1 and themselves.

For example, the number 12 is composite because it can be formed by multiplying 2 and 6 or 3 and 4.

🎢 Optimizing the Program

While the provided program is effective, consider exploring and implementing optimizations for larger numbers, such as checking divisors up to the square root of the number for improved efficiency.

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