Question 2.8: Create a function that finds how many prime numbers there are, up to the given integer.
Examples
primeNumbers(10) ➞ 4
// 2, 3, 5 and 7
primeNumbers(20) ➞ 8
// 2, 3, 5, 7, 11, 13, 17 and 19
primeNumbers(30) ➞ 10
// 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29
Solution:
package com.company;
import java.util.Scanner;
public class lab2Problem08 {
static int primeNumber(int n) {
int d=0;
for (int i = 2; i <= n; i++) {
int c = 0;
for (int j = 2; j <= i; j++) {
if (i % j == 00) {
c++;
}
}
if (c < 2) {
d++;
}
}
return d;
}
public static void main (String[]args){
Scanner Obj = new Scanner(System.in);
while(true){
System.out.println("Input a number: ");
int n = Obj.nextInt();
int r = primeNumber(n);
System.out.println("total prime number is: "+ r);
for (int i = 2; i <= n; i++) {
int c = 0;
for (int j = 2; j <= i; j++) {
if (i % j == 00) {
c++;
}
}
if(c < 2)
{
System.out.print(" "+i);
}
}
System.out.println();
}
}
}
