Homework Assignment, Need some help

[xdrazkalnytex]

I fill in the parts, i got the subtraction and multiplication to work , but the addition and quotient doesn't work. For the quotient I don't know how to do reciprocals. I got the program to work, but 2 of the printout is wrong... Would someone help me?

// Rational.java

public class Rational
{
    private int n; // numerator
    private int d; // denominator

    // Return the greatest common divisor (gcd) of a and b.
    private static int gcd(int a, int b)
    {
        // TBD
      if( a < 0) a = -a;
      if( b < 0) b = -b;
      if( 0 ==b)
        return a;
      else
        return gcd(b, a & b);
    }

    // Construct a rational number given its numerator and denominator.
    public Rational(int n, int d)
    {
        // TBD
      this.n = n;
      this.d = d;           
    }

    // Return the sum of this number and b.
    public Rational plus(Rational b)
    {
        // TBD
      int numerator = (this.n * b.d ) + (this.d * b.n);
      int denominator = (this.d * b.d);
      return new Rational(numerator, denominator);
    }

    // Return the difference of this number and b.
    public Rational minus(Rational b)
    {
        // TBD
      int numerator = (this.n * b.d ) - (this.d * b.n);
      int denominator = this.d * b.d;
      return new Rational(numerator, denominator);
    }

    // Return the product of this number and b.
    public Rational times(Rational b)
    {
        // TBD
      int numerator = (this.n * b.n );
      int denominator = (this.d * b.d);
      return new Rational(numerator,denominator);
    }

    // Return the quotient of this number and b.
    public Rational over(Rational b)
    {
        // TBD   
      int numerator = (this.n * b.d );
      int denominator = (this.d * b.n);
      return new Rational(numerator,denominator);
    }

    // Return true if this number equals b, false otherwise.
    public boolean equals(Rational b)
    {
        // TBD
      boolean equals = this.n != this.d;
      return (equals);
    }

    // Return a string representation of this number.
    public String toString()
    {
        // TBD
        String result;

        if (n == 0)
            result = "0";
        else
            if (d == 1)
                result = n + "";
            else
                result = n + "/" + d;
    
        return result;
    }

    // Test driver.
    public static void main(String[] args)
    {
        Rational a = new Rational(1, 3);
        Rational b = new Rational(2, 3);
        System.out.println("Should print 1/1: " + a.plus(b));
        System.out.println("Should print true: " + b.minus(a).equals(a));
        System.out.println("Should print 2/9: " + a.times(b));
        System.out.println("Should print 1/2: " + a.over(b));
    }
}

[Diargg]

First, use [code] tags. They'll make your code far more readable.

Second, when you say " 2 of the printout is wrong" - Which 2? Can you show us what is wrong? What are they supposed to say?

[xdrazkalnytex]

> run Rational
Should print 1/1: 9/9
Should print true: true
Should print 2/9: 2/9
Should print 1/2: 3/6
>

first printout which should be 1/1 (suppose to be addition)
last printout which should be 1/2 (suppose to be division)

[Diargg]

First, use [code] tags. They'll make your code far more readable.

Also,
Can you say what is wrong with the answers you get?

[xdrazkalnytex]

it shows the wrong print out ,

and what is [code] tags?

[Diargg]

But what is wrong with it, beyond not being right? Should the numbers be different? Should they mean different things? (ie 3/4 means .75 )

Edit your initial post to put [code ] and [/code] around your Java code

[xdrazkalnytex]

it should print out what what the print out said,
like 1/1 should be 1/1 and so on.

[Diargg]

So what is the difference between 9/9 and 1/1? Are they the same?

[xdrazkalnytex]

it supposed to print out 1/1 , but i guess 9/9 will do

[Diargg]

One last try I guess.

Read this. Are you familiar with how fractions work? All of the code you need is present in the example you provided in the first post. The code isn't correct, and we can discuss that, but first you need to understand what you need to do to fix the problem.

[JosAH]

Why have you implemented that gcd( ... ) method in your class? You're not using it ...

kind regards,

Jos

[Sierra]

I have a general hint for you: Never use the same name for local and class attributes like you do... ;)

First reads as it does because it is correct. 9/9 == 1/1 - you just need to cut it down.
Last reads as it does because it is correct. 3/6 == 1/2 - you just need to cut it down.

Add a method that trims it down - you will maybe need gcd() for that ... ;)

[JosAH]

Given the toString() method I don't think 1/1 is ever printed out; I also don't think that code was written by the OP ...

kind regards,

Jos

[Sierra]

@JosAH: I agree to both and I think it is part of the homework to find a solution for the correct output before calling toString()... so he should give it a try. ;)

[JosAH]

@JosAH: I agree to both and I think it is part of the homework to find a solution for the correct output before calling toString()... so he should give it a try. ;)

Ah, ok, so all we can do (and have to do) is sit back and enjoy the show ;-)

kind regards,

Jos

[Diargg]

Ah, ok, so all we can do (and have to do) is sit back and enjoy the show ;-)

kind regards,

Jos

/bows

I'm personally a fan of the (a & b) integer being passed about.

[Sierra]

I wonder if that is/should be Euclid's algorithm...?

[JosAH]

I wonder if that is/should be Euclid's algorithm...?

Nah, just a feeble attempt to it; it is utterly incorrect but the OP will find out ...

kind regards,

Jos