Need help with GCD algorithm

[unikiller]

I've been working on this class for about 2-3 weeks and I got everything done except the reducing part. I can't figure it out , I know you have to use the GCD algorithm , but I cannot figure out how to use it :o , Can someone please tell me how to use it ? I know I have to use it in the reduce member but cannot figure out how to use it or how the syntax is supposed to be. Heres my Fraction.H , Fraction.cpp , and main.cpp files

// Fraction.H //
#include <iostream>
#include <fstream>
using namespace std;

class Fraction
{
public:
    Fraction(void);
    Fraction(int n, int d);
    void plus(Fraction second);
    void minus(Fraction second);
    void times(Fraction second);
    void divide(Fraction second);
    void reduce();
    double todecimal();
    void scan(istream& in);
    void print(ostream& out);
    ~Fraction();

private: 
    int num,den;

};



// Fraction.cpp
#include "Fraction.h"

Fraction::Fraction()
{
    num=0;
    den=1;
}


Fraction::Fraction(int n, int d){
    num=n;
    den=d;
}



void Fraction::plus(Fraction second){
    int tempden= den*second.den;
    num=num*second.den + den*second.num;
    den=tempden;
}

void Fraction::minus(Fraction second){
    int tempden= den*second.den;
num=num*second.den - den*second.num;
    den = tempden;}

void Fraction::times(Fraction second){
    num = num*second.num;
    den=second.den*den;
}

void Fraction::divide(Fraction second){
num = num*second.den;
den= den*second.num;
}

void Fraction::scan(istream & in){
    char slash;
    in >> num >> slash >> den;

}


void Fraction::print(ostream & out){
    out << num <<" / " << den;}





double Fraction::todecimal()
{double dec;

    dec=(num*1.00)/(den*1.00);
    return dec;
}

void Fraction::reduce()

{

}





Fraction::~Fraction()
{
}







//main.cpp



#include "Fraction.h"
using namespace std;
int main(){
Fraction first;
Fraction d(1,2);
cout << " Fraction class menu" << endl;
cout << "     "  << endl;
cout << " Please enter fraction in form of 1/2"<<endl;
first.scan(cin);
cout << " What would you like to do ? (fraction will automatically be reduced and given in decimals)"<< endl;
cout << "1. plus" << endl;
cout << "2. minus" << endl;
cout << "3. times"<<endl;
cout << "4. divide"<<endl;

cout << " Make your choice now" << endl;
int choice;
cin >> choice;
switch (choice)
{
case 1:  {
    cout << "Enter a second fraction to be added to";
    d.scan(cin);
    first.plus(d);
    first.reduce();
    cout << endl;
    first.print(cout);
        cout << endl << "Decimal is " << first.todecimal();


    break;}
case 2: {
    cout << " Enter a second fraction to be subtracted from";
    d.scan(cin);
    first.minus(d);
    first.reduce();
    cout << endl;
    first.print(cout);
    cout << endl << "Decimal is " << first.todecimal();
    break;}
case 3: { 
    cout << "Enter a second fraction to be timed by" << endl;
    d.scan(cin);
    first.times(d);
    first.reduce();
    cout << endl;
    first.print(cout);
    cout << endl << "Decimal is " << first.todecimal();
    break;}
case 4:{ cout << "Enter a second fraction to be divided by" <<endl;
        d.scan(cin);
        first.divide(d);
        first.reduce();
        cout << endl;
        first.print(cout);
        cout << endl << "Decimal is " << first.todecimal();
    break;}
default: cout << "ERROR : Menu Choice";
break;

}








}

/* Sample output

Addition

// Fraction class menu

Please enter fraction in form of 1/2
1/2
What would you like to do ? (fraction will automatically be reduced and given i
n decimals)
1. plus
2. minus
3. times
4. divide
Make your choice now
1
Enter a second fraction to be added to1/2

4 / 4
Decimal is 1Press any key to continue

subtraction
Fraction class menu

Please enter fraction in form of 1/2
8/9
What would you like to do ? (fraction will automatically be reduced and given i
n decimals)
1. plus
2. minus
3. times
4. divide
Make your choice now
2
Enter a second fraction to be subtracted from8/9

0 / 81
Decimal is 0Press any key to continue

Times
Fraction class menu

Please enter fraction in form of 1/2
1/2
What would you like to do ? (fraction will automatically be reduced and given i
n decimals)
1. plus
2. minus
3. times
4. divide
Make your choice now
3
Enter a second fraction to be timed by
1/2

1 / 4
Decimal is 0.25Press any key to continue

divide

Fraction class menu

Please enter fraction in form of 1/2
1/2
What would you like to do ? (fraction will automatically be reduced and given i
n decimals)
1. plus
2. minus
3. times
4. divide
Make your choice now
4
Enter a second fraction to be divided by
1/2

2 / 2
Decimal is 1Press any key to continue

*/

Basically I am getting the right answers, just that the fractions do not reduce :( , thanks to anyone in advance that can help , really need help before friday because that is the last day for this semester :o

[unikiller]

nevermind got it finally

[unikiller]

Ok ... nevermind ... don't got it ....

This is what I put

void Fraction::reduce()

{
    int b=den;
    int c;
    int a=num;
    while (b!=0){
        c= a%b;
        a=b;
            b=c;
    }

    num =  a/num;
    den=a;

}

but I put 1/2 + 1/2 , and it should give me 4/4 or 1 , but it's giving me 1/4 or .25 .... weird, can anyone help me out ? 8)

[unikiller]

nevermind finally got it :)

[siddhant3s]

change the lines :

num =  a/num;
den=a;

to

num = num/a;
den= den/a;

I hope it helps