Find prime number using for loop

#1

import java.util.*;

public class Try {

public static void main(String[] args) {
	Scanner scn = new Scanner(System.in);
	int n = scn.nextInt();
	int temp = 0;
	int i = 2;
	for (i = 2; i <= n - 1; i++)
		;
	{
		if (n % i == 0) {
			temp = temp + 1;
		}
	}
	if (temp>1) {
		System.out.println(" prime no");
	} else {
		System.out.println("NON prime no");
	}
}

}

here input given is 7or 9 both gives non prime number y so

#2

Hi @mannarun09_868823821c6da921

import java.util.*;
public class Main {
public static void main(String args[]) {
Scanner s=new Scanner(System.in);
int n=s.nextInt();
int div=2;
while(div<n){
if(n%div==0){
System.out.println(“not prime”);
return;
}
div++;
}
System.out.println(“prime”);

}

}

1 Like
#3

Thanks.
But why not with for loop i need to find out the mistake their. if possible do so…

#4

@mannarun09_868823821c6da921
There is no difference between using for and while loop if i just write all the conditions in for loop it will also run fine

#5

Agree but why still its not running. still error with similar condition as u gave show below with error
THE CODE:
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
int n =s.nextInt() ;
int temp = 0;
for (int Div= 2; Div <= n - 1; Div++);
{
if (n % Div == 0) {
temp = temp + 1;
}
}
if (temp==0) {
System.out.println(n+ " prime no");
} else {
System.out.println(n+ “NON prime no”);
}
}

}

NOW ERROR:-
/Main.java:9: error: cannot find symbol
if (n % Div == 0) {
^
symbol: variable Div
location: class Main
1 error

#6

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#7

M still the same regarding that problem. plz explain it briefly…

#8

Please initialize the div variable outside the for then it will run fine.

#9

done but still same either u give 11 or 10 both gives same answer.

please
1 write a program to find weather the number is prime or not in for loop… And
2 how to count total no that are prime between 1to 100.