Prime number

This is a Java program to check whether a given number is prime or not.

A prime number is a non-negative integer which is divisible only by 1 and itself. For example, Five being divisible by only one and five, is a prime number. Six, on the other hand is divisible by one, two, three and six and hence is not a prime number.

PROGRAM CODE

import java.io.*;
class prime
{
public void main()throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a number");
int a=Integer.parseInt(br.readLine());
int flag=0;  
for(int i=2;i<=a/2;i++)                                              
{
if (a%i==0)
{
flag=1;
break;}}
if(flag==0)
System.out.println("PRIME");
else
System.out.println("NOT PRIME");
}}

Comments

  1. Unknown12 March 2014 at 10:31

    why do such jhanjhat??? I'll give a simpler program for prime number:-


    import java.util.*;
    class p20
    {
    public static void main()
    {
    Scanner sc=new Scanner(System.in);
    System.out.print("Enter a number:");
    int k=0,num=sc.nextInt();
    for(int i=1;i<num;i++)
    {
    if(num%2==0)
    k++;
    }
    if(k==1)
    System.out.println("PRIME NUMBER");
    else
    {
    System.out.println("COMPOSITE NUMBER");
    break;
    }
    }
    }

    ReplyDelete
    Replies
    1. Unknown29 January 2015 at 06:57

      ty this was simple and good ty again

      Delete
    2. Unknown4 October 2015 at 08:38

      it is wrong
      the statement "if(num%2==0)"
      should be "if(num%i==0)"

      Delete
    3. Unknown8 January 2016 at 23:08

      "break;"-this statement should not be there
      except that,its all fine

      Delete
    4. Unknown21 September 2017 at 21:27

      the top code is the best efficient ...
      urs is also correct with the above correction but it is time consuming

      Delete
  2. Anonymous10 September 2015 at 09:08

    This comment has been removed by the author.

    ReplyDelete
  3. Anonymous10 September 2015 at 09:25

    kid ur program is wrong.compile and check it.LoL

    ReplyDelete
  4. Unknown17 December 2015 at 21:06

    A great site for help of the icse.All developers of the site should be honoured.

    ReplyDelete
  5. Unknown20 July 2017 at 00:08


    Divide a given number by its divisors and if find no whole-number factor [apart from 1 and itself] then I will call my number a prime number.The driving force of the operation, or what separates Primes from non-Primes is the division.

    ReplyDelete

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