C# function to check a number is prime or not

C# function to check whether a number is prime or not

In this tutorial, we will discuss the concept of the C# proram to check whether a Number is Prime or Not – using a user-defined function

In this post, we are going to learn how to check whether a number is prime or not, using a user-defined function in C# programming language with Example program

 

Prime number

The number that can be divided by 1 and itself. it is called a prime number

for Example 2,3,5,7,11,13…

C# example to check whether a Number is Prime or Not

Check the prime number using a function– method 1

This program allows you to enter the input of a positive number and then it will check whether the given number is a prime number or not, using the function in C# language

Program 1

using System;

public class CheckPrime
{
     public static bool Check_Prime(int num){
          for (int i=2; i<num; i++)
              if(num%i==0)
              return false;
         return true;
         
     }
    public static void Main(string[] args)
    {
        Console.Write ("Input a number: ");
        int n=Convert.ToInt32(Console.ReadLine());
        
        if(Check_Prime(n))
        Console.WriteLine (n+" is a prime");
        else
        Console.WriteLine (n+" is not a prime");
         
    }
}

When the above code is executed, it produces the following result

Case 1

Input a number: 13
13 is a prime

 

Case 2

Input a number: 20
20 is not a prime

 

Check the prime number using a function– method 2

This program allows one to enter input of a positive number and then it will check whether the given number is a prime number or not, using the function in C# language

Program 2

//function to check a number prime or not
using System;

public class CheckPrime
{
     public static int Check_Prime(int number){//uer define function 
     int i;
          for (i=2; i<=number-1; i++){
              if(number%i==0){
              return 0;
              }
          }
        if(i==number){
              return 1;
              }
              return 0;
         
     }
    public static void Main(string[] args)
    {
        Console.Write ("Input a number: ");
        int number=Convert.ToInt32(Console.ReadLine());
        int res= Check_Prime(number);
        if(res==0){
        Console.WriteLine ("{0} is not a prime number",number);}
        else{
        Console.WriteLine ("{0} is a prime number",number);}
         
    }
}

When the above code is executed, it produces the following result

Case 1

Input a number: 17
17 is a prime number

 

Case 2

Input a number: 22
22 is not a prime number

 

 

 

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