# Thread: Adding and Subtracting positive or negative two numbers of any length with strings

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## Adding and Subtracting positive or negative two numbers of any length with strings

You are to design a Java application to carry out additions and subtractions for numbers of any length. A number is represented as an object which includes a sign and two strings for the whole and decimal parts of the number. And, the operations must be done by adding or subtracting characters directly. You are not allowed to convert these strings to numbers before the operation.

The program must use a "Number" class which includes at least the following methods:

Number ( );

Number (double n);

Number subtract (Number RHS);

String toString ( );

The below code is what our teacher gave us to start with, but it needs to add and subtract positive or negative numbers of any length. This code only adds positive numbers. Need to write code for subtraction . help

Java Code:
```
import java.util.Scanner;

public class Number{
private String whole;
private String decimal;
private String sign;

public static void main (String[] args){

System.out.println("Enter two numbers");
Scanner keyboard = new Scanner(System.in);
Double firstNumber = keyboard.nextDouble();
Double secondNumber = keyboard.nextDouble();

Number x = new Number (firstNumber);
Number y = new Number (secondNumber);

System.out.println ("x = " + x);
System.out.println ("y = " + y);
System.out.println("x + y = " + sum);
Number subtract = x.Subtract(y);
System.out.println("x - y = " + subtract);
}

public Number(){
whole = "0";
decimal = "0";
sign = "+";
}

public Number (double n){
whole = "0";
decimal = "0";
sign = "+";
String temp = new Double(n).toString();
if (temp.charAt(0) == '-'){
sign = "-";
temp = temp.substring(1);
}
int pos = temp.indexOf(".");
if (pos == -1)
whole = temp;
else
{
whole = temp.substring (0,pos);
decimal = temp.substring (pos+1);
}
}

this.alignWhole (RHS);
this.alignDecimal (RHS);
}

private void alignWhole (Number RHS){
int firstWholeL = this.whole.length();
int secondWholeL = RHS.whole.length();
int dif = firstWholeL - secondWholeL;
if (dif > 0){
for (int i = 1; i <= dif; i++)
RHS.whole = "0" + RHS.whole;
}
else if (dif < 0)
{
dif = Math.abs (dif);
for (int i = 1; i <= dif; i++)
this.whole = "0" + this.whole;
}
}

private void alignDecimal (Number RHS) {
int firstDecimalL = this.decimal.length ( );
int secondDecimalL = RHS.decimal.length ( );
int dif = firstDecimalL - secondDecimalL;

if (dif > 0)
{
for (int i = 1; i <= dif; i++)
RHS.decimal = RHS.decimal + "0";
}

else if (dif < 0)
{
dif = Math.abs (dif);
for (int i = 1; i <= dif; i++)
this.decimal = this.decimal + "0";
}

}

Number sum = new Number();
sum.decimal = "";
int carry = 0;
int decimalL = this.decimal.length();
for (int i = decimalL -1; i >= 0; i--)
{
char firstC = this.decimal.charAt(i);
char secondC = RHS.decimal.charAt(i);
int sumX = (firstC - 48) + (secondC - 48) + carry;
char sumC = (char)((sumX % 10) + 48);
carry = sumX / 10;
sum.decimal = sumC + sum.decimal;
}

sum.whole = "";
int wholeL = this.whole.length();
for (int i = wholeL -1; i >= 0; i--)
{
char firstC = this.whole.charAt (i);
char secondC = RHS.whole.charAt (i);
int sumX = (firstC - 48) + (secondC - 48) + carry;
char sumC = (char)((sumX % 10) + 48);
carry = sumX / 10;
sum.whole = sumC + sum.whole;
}

if (carry != 0)
sum.whole = "1" + sum.whole;

return sum;
}

public String toString()
{
return sign + whole + "." + decimal;
}
}```
Last edited by beginner234; 02-05-2014 at 10:59 PM.

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## Re: Adding and Subtracting positive or negative two numbers of any length with string

That's not how it works. You need to make a start, not just dump the homework and ask for help.

You will probably first want to write out on a piece of paper what your code needs to do. It will probably help to use the addition code that is given to you as a source of inspiration. Which probably means that you first need to figure out how that code works and why it does what it does.

4. ## Re: Adding and Subtracting positive or negative two numbers of any length with string

To the OP: when the first words of your post are "You are to design a Java application..." I *IMMEDIATELY* stop reading and stop caring. The "HOMEWORK ALERT" is triggered and it stops me from reading any further. If you can't handle the CS/Programming/Java class, then by all means drop it, but don't let us do your homework. At least pay me for it. Oh no, I won't do that either. I smell hamburgers and fries....

5. Just a guy
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## Re: Adding and Subtracting positive or negative two numbers of any length with string

Originally Posted by SurfMan
I smell hamburgers and fries....
Damn you, now I smell them too.

6. ## Re: Adding and Subtracting positive or negative two numbers of any length with string

Originally Posted by gimbal2
Damn you, now I smell them too.
I do't sbell adythi'g because by dose is blocked ...

ki'd regards,

Jos *hatchoo!*

7. Just a guy
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## Re: Adding and Subtracting positive or negative two numbers of any length with string

Chili Con Carne with extra chili (or Chili Con Pollo, equally tasty). That will clear your nose up right away, guaranteed.

8. ## Re: Adding and Subtracting positive or negative two numbers of any length with string

Originally Posted by gimbal2
Chili Con Carne with extra chili (or Chili Con Pollo, equally tasty). That will clear your nose up right away, guaranteed.
Ok, by dose is full of chilli beads; dow what?

ki'd regards,

Jos (<--- still full of it; maybe Dr. JosAHs jenever therapy will help)

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## Re: Adding and Subtracting positive or negative two numbers of any length with string

*sings* Mr booze, mr booze. Mister b double o z e that sure spells boohoooooooooze...

Its Friday!

10. ## Re: Adding and Subtracting positive or negative two numbers of any length with string

Originally Posted by gimbal2
*sings* Mr booze, mr booze. Mister b double o z e that sure spells boohoooooooooze...

Its Friday!
Oh dear, the poor soul must've lost his mind; quick! finish him off!

kindest regards,

Jos (<--- switches on his chainsaw to perfom his noble deed)

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