﻿ C# - Check whether a given number is prime or not

# C#: Check whether a given number is prime or not

## C# Sharp For Loop: Exercise-32 with Solution

Write a C# Sharp Program to determine whether a given number is prime or not.

Visual Presentation:

Sample Solution:

C# Sharp Code:

``````using System;  // Importing necessary namespace

public class Exercise32  // Declaration of the Exercise32 class
{
public static void Main()  // Main method, entry point of the program
{
int num, i, ctr = 0;  // Declaration of variables num, i, and ctr as integers

Console.Write("\n\n");  // Displaying new lines
Console.Write("Check whether a given number is prime or not:\n");  // Displaying the purpose of the program
Console.Write("-----------------------------------------------");  // Displaying a separator
Console.Write("\n\n");  // Displaying new lines

Console.Write("Input a number: ");  // Prompting the user to input a number
num = Convert.ToInt32(Console.ReadLine());  // Reading the number entered by the user

// Loop to check if the number is prime
for (i = 2; i <= num / 2; i++)
{
if (num % i == 0)
{
ctr++;  // Incrementing the counter if the number has divisors other than 1 and itself
break;  // Exiting the loop if a divisor is found
}
}

// Checking the value of ctr to determine if the number is prime or not
if (ctr == 0 && num != 1)
{
Console.Write("{0} is a prime number.\n", num);  // Displaying if the number is prime
}
else
{
Console.Write("{0} is not a prime number\n", num);  // Displaying if the number is not prime
}
}
}
```
```

Sample Output:

```Check whether a given number is prime or not:
-----------------------------------------------
Input  a number: 53
53 is a prime number.
```

Flowchart:

C# Sharp Code Editor:

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