I'm creating a program that adds fractions together. That being said however, my program does not seem to be responding correctly. Everytime I run the client code, it outputs
18, when I want it to add 2/6 and 1/6.

``````// Constructor //

public class RationalNumber
{
int num;
int den;

private int gcd(int x, int y)
{
while(y != 0)
{
int temp = x % y;
x = y;
y = temp;
}
return x;
}

public RationalNumber(int numerator, int denominator)
{
if(denominator == 0)
{
throw new IllegalArgumentException("You can't divide by zero.");
}
else
{
num = numerator;
den = denominator;
}
}

public RationalNumber()
{
this (0,1);
}

public boolean equals(Object o)
{
if (o instanceof RationalNumber)
{
RationalNumber other = (RationalNumber) o;
int r1 = this.gcd(num,den);
int r2 = this.gcd(other.getNumerator(),other.getDenominator());
return num/r1 == other.num/r2 && den/r1 == other.den/r2;
}
else
{
return false;
}
}

public int getDenominator()
{
return den;
}

public int getNumerator()
{
return num;
}

public void reduce()
{
int d;
while (true)
{
d = this.gcd(this.num,this.den);
if (d == 1)
{
return;
}
this.num /= d;
this.den /= d;
}
}

{
int commonDen = den * r1.getDenominator();
int num1 = num * r1.getDenominator();
int num2 = r1.getNumerator() * den;
int sum = num1 + num2;
return sum;
}

public String toString()
{
if (den == 1)
{
return num + "";
}
else
{
return num + "/" + den;
}
}

}``````
``````// Client Code //

public class RationalNumberTest
{
public static void main (String[] args)
{
RationalNumber r1 = new RationalNumber(2,6);
RationalNumber r2 = new RationalNumber(1,6);

}
}``````

## All 7 Replies

lines 82/83 you add together the numerators (after getting them over the LCM denominator), but you forgot to divide by the LCM denominator - ie you calc
(2*6) + (1*6)
when it should be
((2*6) + (1*6))/(6*6)

But in any case shouldn't add return a RationalNumber, rather than an int (which will be 0 in your test case because the answer is <1

Thank you for your response. Unfortunately, it still outputs the same answer.

``````public int add(RationalNumber r1)
{
int commonDen = den * r1.getDenominator();
int num1 = num * r1.getDenominator();
int num2 = r1.getNumerator() * den;
int sum = num1 + num2;
int total = sum / den * getDenominator();
}``````

That's not exactly what I said in my post. You can't ignore the brackets!...
18 / 6 * 6 = 18
18 / (6*6) = 1/2

B
Brackets first
O
Orders (ie Powers and Square Roots, etc.)
DM
Division and Multiplication (left-to-right)
AS

Split your calculations using this order of operations

``````int commonDen = den * r1.getDenominator();
int num1 = num * r1.getDenominator();
int num2 = r1.getNumerator() * den;
int sum = num1 + num2;
int total =  sum / (den * den);

Like so?
My program now outputs zero.

Come on! print some values out as you initialise them! Test your code!!
i.e.

``System.out.println("value of sum: "+sum);//print after your initialisation of sum``

Outputs zero just like I said in my first post. Read it again.

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