what i am further to do..I got a Prime Numbers to be print ,non prime numbers are am not able to print

Question

Input:20
Output:0 is not a Prime
       1 is not a prime
       2 is a prime 
       3 is a prime 
       4 is not a prime 
       5 is a prime
       20 is not a prime(upto number 20)

My Class

public class Prime{
    public static void main(String[] args){
        int number=20;
        int p;
        for(int i=2;i<number;i++){
            p=0;
            for(int j=2;j<i;j++){
                if(i%j==0){
                    p=1;
                }
            }
            if(p==0){
                System.out.println(i+" "+"Is Prime");
            }
        }
    }
}

In the above program I printed the prime numbers,How to print both prime and non prime numbers in it?Thanks in advance! check it from 0 is not a Prime, 1 is not a prime, 2 is a prime, 3 is a prime, 4 is not a prime, 5 is a prime, 7 is a prime, 8 is not a prime ,continues upto n given

Possible duplicate of [Prime Number Generator Logic](http://stackoverflow.com/questions/20435289/prime-number-generator-logic) — rghome, Dec 20 '16 at 10:22
There are zillions of pages out there on prime-number generator algorithms, some on this site. — rghome, Dec 20 '16 at 10:23

anacron · Answer 1 · 2016-12-21T12:06:54.180

0

Add an else block to the if statement that can print non-prime numbers.

if(p==0){
    System.out.println(i+" "+"Is Prime");
}
else {
    System.out.println(i+" "+"Is not Prime");
}

Update:

Also modify your for loop statement like so:

System.out.println("0 is not Prime");
System.out.println("1 is not Prime");
for(int i=2;i<=number;i++){

This will iterate from 0 to 20.

edited Dec 21 '16 at 12:06

answered Dec 20 '16 at 10:28

anacron

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Yup! but if i added these lines it gives the output from 2 to 19 only.I have to start with the 0 to 20.0 is not a prime 1 is not a prime. 2 is a prime.Likewise upto 20 is not a prime. – AngMic Dec 20 '16 at 18:35
0 and 1 is not a Prime .If am declaring the for loop as like for(int i=0;i<=number;i++).It returns the output 0 is a prime 1 is a prime. – AngMic Dec 21 '16 at 12:02
By definition, 0 and 1 are not prime numbers and are generally not considered while calculation. You can choose to print them separately before starting your loop.. – anacron Dec 21 '16 at 12:06

score 0 · Answer 2 · edited Oct 14 '22 at 07:43

Modify condition for not prime also check if value is 0 0r 1 then print number is not prime.

public static void main(String[] args) {

    int number=20;
    int p;
    if(number==0 || number ==1){
         System.out.println(number+" "+"is not a Prime");
    }
    for(int i=0;i<number;i++){
        p=0;
        
        for(int j=2;j<i;j++){
            if(i%j==0){
                p=1;
            }
        }
        if(i==0 || i ==1){
         p=1;
         }
        if(p==0){
            System.out.println(i+" "+"Is Prime");
        }else{
            System.out.println(i+" "+"is not a Prime");
        }
    }
}

what i am further to do..I got a Prime Numbers to be print ,non prime numbers are am not able to print

2 Answers2