[djwendt]

I know there are other posts about this, but none of them really help me with my problem. The assignment is to create a program that will ask how many numbers you want to test, then have you input the numbers to test. My code is returning the remainder amount:
9:4
8:4
7:3
6:3
5:2
4:2
3:1
2:1
1:NOT PERFECT

I need it to also display the factors in descending order.

So here is my method to test:

   public static boolean testPerfect(int number2)
    {

        int sum = 0;
        boolean testing = false;


        for (int i = 1; i < number2; i++ )
        {
            if ( i % number2 == 0)
            sum = sum + i;
            testing = true;

        }  return testing;

    } // end testPerfect

I know something is messed in my for loop due to the return of all numbers, except #1, to display factors/modulus.

This is my method to print factors, which I think is all correct except for displaying ALL factor in descending order.

public static void printFactors(int print)
    {
        int total = 0;

        for (int divisor = 1; divisor < print; ++divisor)
        {
            if(divisor == print/2)
                {

                    System.out.printf("%d", divisor);

                }


        }
    }

I know I need to decrement divisor, but when I do i get a infinite loop. Do I need to take the if statement out of the for loop?

As stated in the rules, I'm not looking for anyone to correct this for me just some help on where I need to fix my problems.

Thanks!

[macosxnerd101]

It makes more sense to me that if print%divisor == 0 to print the divisor. Also, you could make sure your divisor < print/2. Now- do you want all the factors or all the prime factors of each number?

[SwiftStriker00]

Here is what a better print factors looks like:

public static void printFactors( int number ){
		for( int i = 1; i <= number /2; i ++ ) {
			
			if( number % i == 0 ){
				System.out.print( i + " " );
			}
		}
		
		System.out.println( number );
	}

What is this doing? It is stepping though each number up until our input number ( lets use 10 as an example ). We are going to start at 1, because we don't want to divide by zero. Then we don't need to go past half the input value, so we will continue until number / 2 . note, i used <= and not just =, because if number is an even number, we will want to check that too!

Now for inside the loop, what is a factor? something we can divide the input by evenly. Modulus is a great tool for this, by saying number % i , that will divide i by number and return the remainder. Well, if the remainder is 0, then we know it evenly divides into number.

Lastly we print out the number itself because, anything % 1 = anything.

[djwendt]

@macosxnerd101 - It needs to be all the factors.


Thanks for the help you two. Will try that after a bit and let you know how it goes.

[djwendt]

So that helped with the printing factors but I need them to be in descending order. My thinking was to decrement i (i--) but that got me nowhere(infinite loop).

Also it's printing the factors for non-perfect numbers. That has to do with my testPerfect method (right?), but what is wrong that makes it print incorrectly.

Example:
9: 1 3
8: 1 2 4
7: 1
6: 1 2 3
5: 1
4: 1 2
3: 1
2: 1
1: NOT PERFECT

Do I need to compare sum to number2, if they are the same then it would be true? If so, where? I've tried a separate if statement, but that didn't work.

[pbl]

Complicated for nothing

		for(int i = 2; i < 100; ++i) {
		    int total = 0;
		    System.out.print(i + ": ");
		    for(int j = 1; j < i-1; ++j) {
		    	if(i % j == 0) {
		    		System.out.print(" " + j);
		    		total += j;
		    	}
		    }
		    if(total == i)
		    	System.out.print("    ......perfect");
		    System.out.println();
		}

[djwendt]

I'm not sure what you mean with that post. I have a main method that I haven't posted that returns most everything, it calls testPerfect to calculate the sumation of the factors & calls printFactors (which is void) to print the factors if the number entered is perfect. There's something wrong with the testPerfect for loop, but I just can't see it. Also how do I print the factors in descending order? I've tried decrementing i, but that results in an infinite loop.

[pbl]

If we have to do everything...

public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    System.out.print("Enter a number: ");
    int number = scan.nextInt();
    testPerfect(number);
}

static void testPerfect(int i) {
    int total = 0;
    System.out.print(i + ": ");
    int nbValue = 0;
    int[] value = new int[500];
    for(int j = 1; j < i-1; ++j) {
    	if(i % j == 0) {
    		value[nbValue++] = j;
    		total += j;
    	}
    }
    for(int j = nbValue; --j >= 0;)
      System.out.print(" " + value[j]);
    if(total == i)
    	System.out.print("    ......perfect");
    System.out.println();
}

Happy coding

[djwendt]

Thank you for that but I can't use arrays on this assignment.
Here is what i have for a main

public static void main ( String args[])
    {

        Scanner input = new Scanner ( System.in );

        int number = 0;
        int number2 = 0;

        do
        {
        System.out.print("How many numbers would you like to test? ");
        number = input.nextInt();
        } while (number < 1);


        for (int count = 0; count < number; ++count)
        {
            System.out.print("Please enter a possible perfect number: ");
            number2 = input.nextInt();
            testPerfect(number2);




            if (testPerfect(number2)== true)
            {
                System.out.printf("%d: ", number2);
                printFactors(number2);
                System.out.println("");
            }
            else

            {
                System.out.printf("%d:NOT PERFECT\n", number2);
            }

        }

    }

[pbl]

If you can't use array just no way you will remember the first divisor and print them in reverse order. You will have to store them somewhere

[djwendt]

So this is what I finally ended up with :

import java.util.Scanner;

public class djwendt_Perfect
{
    public static void main (String args [])
    {
        int number = 0;   // variable for how many to test
        int number2 = 0;  // variable for possible perfect
     
        Scanner input = new Scanner (System.in);

        do 
        {
            System.out.print("How many numbers would you like to test? ");
            number = input.nextInt();
        } while (number < 1); // end do...while
        
        for (int count = 0; count < number; ++count)
        {
            System.out.print("Please enter a possible number: ");
            number2 = input.nextInt();
        
            if (testPerfect(number2))
            {
                System.out.printf("%d:", number2);
                printFactors(number2);
                System.out.println("");
            } // end if statement
            else
            {
                System.out.printf("%d:NOT PERFECT\n", number2);
            } // end else
        }// end for loop 
    } // end main
    // method to test if number is Perfect
    public static boolean testPerfect(int test)
    {
        int sum = 0;            // variable to hold sumation
        boolean result = false; // variable 
        
        if (test == 0)
        {
            result = false;
        } 
        for (int counter = 1; counter <= (test/2); ++counter)
        {
            if (test % counter == 0)
            {
                sum = sum + counter;
            } // end if statement
        } // end for loop
        
        if  (sum == test)
        {
            result = true;
                      
        }return result; // end if statement
    } // end testPerfect method
    // method that prints the factors in descending order
    public static void printFactors(int print)
    {
        
        int total = 0; // variable to hold mod number

        for (int factors = print - 1; factors > 0; factors--)
        {
            total = print % factors;
        
            if (total == 0)
            
                System.out.print(factors + " ");
            
        } // end for loop
    }
}

I only have I minor problem, it's printing 0(zero) as a perfect number.