1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | class PrimeNo{ public static void main(String args[]){ int num = Integer.parseInt(args[0]); int flag=0; for(int i=2;i<num;i++){ if(num%i==0) { System.out.println(num+" is not a Prime Number"); flag = 1; break; } } if(flag==0) System.out.println(num+" is a Prime Number"); } } |

import java.util.*;

class prime_number

{

static Scanner sc = new Scanner (System.in);

public static void main()

{

System.out.print(“Enter A Number : “);

int n=sc.nextInt();

if(n==2)

{

System.out.println(“\n2 is a prime number”);

}

for(int i=2;i<n;i++)

{

if(n%i==0)

{

System.out.print("\n"+n+" is not a prime number");

break;

}

else

{

System.out.print("\n"+n+" is a prime number");

break;

}

}

}

}

the for loop should be continued only till n/2, because a number after this cannot divide n.

Yea , but it wont’s work for 3 and 5 . Check it.

why you will use scanner object

import java.util.*;

import java.io.*;

public class one

{

public static void main(String args[])

{

int num;

int flag=0;

System.out.println(“Enter an integer to check ?”);

Scanner in = new Scanner(System.in);

num = in.nextInt();

for(int i=2;i<num;i++){

if(num%i==0)

{

System.out.println(num+" is not a Prime Number");

flag = 1;

break;

}

}

if(flag==0)

System.out.println(num+" is a Prime Number");

}

}

What is the use of flag here?

why did you use the flag .why did you assign 0 and 1 in the flag.it is only comes under true or false statement.

In first 2 is considered as non prime no…!