code 22.txt

/*
 * Program: Using the While Loop
 * Date: 18/3/2019
 * Programmer: J.Sookha
 * Description: Learning to use the while loop (pre-condition)
 *		2 parts
 *		determine and print the factors of a number
 *		determine if a number is a prime number or not
*/
package usingwhileloop2; 

import java.util.Scanner; 

public class usingwhileloop2{
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int intNumber; 

		System.out.print("Please enter any number: ");
		intNumber = sc.nextInt();

		// examples 
		// 6 - 1 2 3 & 6 
		// 10 - 1 2 5 & 10
		
		int intCount; 
		intCount = 1; 

		int intFactor; 
		
		// loop to run from 1 to the number entered / new condition is more efficient (runs only half)
		// because there are no factors after the halfway point 

		while (intCount <= (intNumber / 2)) // original condition (intCount <= intNumber)
		{
			if ((intNumber % intCount) == 0) // if the number is divisible - its a factor
			{
				// System.out.println(" Factor is " + intCount); // printing factors

				intFactor = intCount; // keeping count instead of printing for 'prime numbers'
			}
			intCount = intCount + 1; // incrementing the count to test the next number
		}	
		
		// this line below printed the number that was entered - the number is a factor of itself 
		// and since the loop did not now run till the end - we needed to manually print the number 
		// and make it look like we worked out that this is a factor

		// System.out.println(" Factor is " + intNumber); 
		
		if (intFactor == 1) // this was my decision to work out if the number entered was a prime number or not 
			System.out.println("Prime number");
		else 
			System.out.println("NOT a Prime number");		
	}
}