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Check if a number is prime or not!


Posted Date: 01-Jul-2008  Last Updated:   Category: C# Syntax    
Author: 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");
num1 = Convert.ToInt32(Console.ReadLine());
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;

}


}
Console.ReadLine();
}
}
}


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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: ");
num = Convert.ToInt32(Console.ReadLine());
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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