Thread: Math Remainder Issue

Try debugging the code by printing out the results of each computation with a println() statement so you can see the results of each expression. Be sure to add labels to all the printouts. Something like this:

        System.out.println("ae="+ae);

Change ae to the names of the variables used in your code.

If you can't understand what is happening in the code, copy and paste here what is printed out by the added printlns and ask questions about the results that you don't understand.

displays a value of 0

A common reason for that is the code is using integer arithmetic: 4/10 = 0


Please copy and paste here the console from when you execute the program that shows the input and its output.
On windows: To copy the contents of the command prompt window:
Click on Icon in upper left corner
Select Edit
Select 'Select All' - The selection will show
Click in upper left again
Select Edit and click 'Copy'

Paste here.

I am glad to say that given the wise advice of Norm, I came up with a working program. I had to test a few things before finally getting the program right.
1. The main problem I was experiencing was due to the integer arithmetic issue -- I solved this by simply making the variables of type double
2. I was unable to carry the variables to the next expression as well as print them in the same form -- My solution was to create a third set of variable to specifically print from.
3. Simple mathematical errors

Now my problem is that when I debug the code by printing out each set of computations, I recieve long decimals that are a fraction off of the true value. Such as "2.6999999999999886" when it should really be "2.70".

import java.util.Scanner;
 
 
public class Change {
 
	private static Scanner input;
 
	public static void main(String[] args) {
		input = new Scanner (System.in);
 
		double change; //User input value
		double hund, twend, tend, fived, oned, quarters , dimes, nickels;
		double afthund, afttwend, afttend, aftfived, aftoned, aftquarters, aftdimes, aftnickels;
		double hundreds, twenties, tens, fives, ones, twentyfivecents, tencents, fivecents;
 
		System.out.println("How much money would you like me to give you change for?");
		change = input.nextDouble();
 
			hund = change; 
			afthund = hund % 100.00; 
			hund = hund - afthund;
			hundreds = hund / 100;
 
			System.out.println("lna1= " + hund);
			System.out.println("lna2= " + afthund);
			System.out.println();
 
 
			twend = afthund;
			afttwend = twend % 20.00;
			twend = twend - afttwend;
			twenties = twend / 20;
 
			System.out.println("lnb1= " + twend);
			System.out.println("lnb2= " + afttwend);
			System.out.println();
 
 
			tend = afttwend; //Divide aftwend by 10.00 (tend)
			afttend = tend % 10.00; //then get amount left over (afttend)
			tend = tend - afttend;
			tens = tend / 10;
 
			System.out.println("lnc1= " + tend);
			System.out.println("lnc2= " + afttend);
			System.out.println();
 
 
			fived = afttend;
			aftfived = fived % 5.00;
			fived = fived - aftfived;
			fives = fived / 5;
 
			System.out.println("lnd1= " + fived);
			System.out.println("lnd2= " + aftfived);
			System.out.println();
 
 
			oned = aftfived;
			aftoned = oned % 1.00;
			oned = oned - aftoned;
			ones = oned / 1.00;
 
			System.out.println("lne1= " + oned);
			System.out.println("lne2= " + aftoned);
			System.out.println();
 
 
			quarters = aftoned;
			aftquarters = quarters % .25;
			quarters = quarters - aftquarters;
			twentyfivecents = quarters / .25;
 
			System.out.println("lnf1= " + quarters);
			System.out.println("lnf2= " + aftquarters);
			System.out.println();
 
 
			dimes = aftquarters;
			aftdimes = dimes % .10;
			dimes = dimes - aftdimes;
			tencents = dimes / .10;
 
			System.out.println("lng1= " + dimes);
			System.out.println("lng2= " + aftdimes);
			System.out.println();
 
 
			nickels = aftdimes;
			aftnickels = nickels % .05;
			nickels = nickels - aftnickels;
			fivecents = nickels / .05;
 
			System.out.println("lnh1= " + nickels);
			System.out.println("lnh2= " + aftnickels);
			System.out.println();
 
 
			System.out.print("Hundreds: " + (int)hundreds); //Print hundreds
			System.out.println();
 
			System.out.print("Twenties: " + (int)twenties); //Print twenties
			System.out.println();
 
			System.out.print("Tens:     " + (int)tens); //Print tens
			System.out.println();
 
			System.out.print("Fives:    " + (int)fives); //Print fives
			System.out.println();
 
			System.out.print("Ones:     " + (int)ones); //Print ones
			System.out.println();
 
			System.out.print("Quarters: " + (int)twentyfivecents); //Print quarters
			System.out.println();
 
			System.out.print("Dimes:    " + (int)tencents); //Print dimes
			System.out.println();
 
			System.out.print("Nickels:  " + (int)fivecents); //Print nickels
			System.out.println();
 
			System.out.print("Pennies:  " + (int)aftnickels); //Print pennies
			System.out.println();
 
	}
 
 
}

Strangely this does not affect the end result (even if the values are not typecasted into integers..)
** Except when there are pennies involved!

Much appreciated,
bzhagar

You should leave the variables as ints and scale them up to the number of cents (*100) vs the number of dollars to keep from having values such as 2.699999999999988

The code needs more testing. Try this value:

		change = 237.77; //input.nextDouble();

NOTE: Your labels on the print out are not the name of the values being printed:

System.out.println("lna1= " + hund);
vs
System.out.println("hund= " + hund);

I'm glad you got it working. See you next time.