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# Check if a number is prime or not!

 Posted Date: 01-Jul-2008 Last Updated: 01-Jul-2008 Category: C# Syntax Author: Rajeev Kumar Dubey Member Level: Silver Points: 10

using System;
using System.Collections.Generic;
using System.Text;

namespace odd_number
{
class Program
{
static void Main(string[] args)
{
int num1;

Console.WriteLine("Accept number");
for (int a = 1; a <=(num1 / 2); a++ )
{
if (num1%a!=0)
{
Console.WriteLine("Number is a prime number");
break;
}

else
{
Console.WriteLine("Number is not prime number");
break;

}

}
}
}
}

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Responses to "Check if a number is prime or not!"
Author: Nathan Stanford    14 May 2010Member Level: Bronze   Points : 1
This code is incorrect. I put in the number 239 and it is a prime number and yet this program says it is not a prime number.

Author: Asif Huddani    15 May 2010Member Level: Gold   Points : 2
Hi,

using System;
using System.Collections.Generic;
using System.Text;

namespace Exercise_1
{
class Prime
{
public void Prime_Number(int number)
{
int i;
for (i = 2; i < number; i++)
{
if (number % i == 0)
{
Console.WriteLine("{0} is not a prime number", number);
break;
}
}
if(i == number)
{
Console.WriteLine("{0} is a prime number", number);
}
}
static void Main(string[] args)
{
int num;
Console.WriteLine("Enter the number: ");
Prime p = new Prime();
p.Prime_Number(num);
}
}
}

Author: mox shah    17 May 2010Member Level: Gold   Points : 2
hello

` using System; using System.Collections.Generic; using System.Text; namespace prime { class Program { static void Main(string[] args) { int num; int result; int i, j; Console.WriteLine("Untill what number u want to show prime number?"); num = Convert.ToInt32(Console.ReadLine()); Console.WriteLine("The prime number between o and ur number are:"); if (num == 2) Console.WriteLine("2"); else { Console.WriteLine("2"); for (i = 3; i <= num; i++) { for (j = 2; j <=num / 2; j++) { result = i % j; if (result!=0) Console.WriteLine(i); } } Console.ReadLine(); } } } }`

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