What may be the reason for this constructor failing to initialize with the given values?-CodePudding

I have been trying to solve an example question from a book and I encountered this problem while initializing the constructor with the values given below. Normally constructor initializes the variables beforehand. When I run the function from a function like Rational_Caller, the member function file given below gives an error as "DIVISION BY ZERO ERROR". Since I initialize the first object with given values in Rational_Caller function, I couldn't figure out why denominator gets the value 0.

this is the header file

// Rational Class header file

#ifndef _RATIONAL_H_
#define _RATIONAL_H_

class Rational
{
public:
    Rational(int = 0, int = 1); // default constructor
    Rational addition(const Rational&); 
    Rational subtraction(const Rational&); 
    Rational multiplication(const Rational&); 
    Rational division(const Rational&); 
    void printRational(); 
    void printRationalAsdouble(); 

private:
    int numerator; 
    int denominator; 
    void reduction(); // function to reduce using great common divisor 

}; 




#endif // !_RATIONAL_H_

this is the member function definitions for the file Rational.h


#include <iostream>
#include "Rational.h" // include definiton of class Rational 

using namespace std; 

Rational::Rational(int n, int d)
{
    numerator = n; 
    denominator = d; 
    reduction(); 
} 


Rational Rational::addition(const Rational& a)
{
    Rational t; 
    
    t.numerator = a.numerator * denominator; 
    t.numerator  = a.denominator * numerator; 
    t.denominator = a.denominator * denominator; 
    t.reduction();
    return t; 

} 

Rational Rational::subtraction(const Rational& s)
{
    Rational t;
    t.numerator = s.numerator * denominator; 
    t.numerator -= denominator * s.numerator; 
    t.denominator = s.denominator * denominator; 
    return t; 

}  

Rational Rational::multiplication(const Rational& m)
{
    Rational t; 
    t.numerator = m.numerator * numerator; 
    t.denominator = m.denominator * denominator; 
    t.reduction(); 
    return t;   
} 

Rational Rational::division(const Rational& v)
{
    Rational t; 
    t.numerator = numerator * v.denominator; 
    t.denominator = denominator * v.numerator; 
    t.reduction(); 
    return t; 

} 


void Rational::printRational()
{
    if (denominator == 0) 
        cout << "\nDIVIDE BY ZERO ERROR!!!" << "\n";
    else if (numerator == 0) 
        cout << 0;
    else
        cout << numerator << '/' << denominator; 
} 


void Rational::printRationalAsdouble()
{
    cout << static_cast<double>(numerator) / denominator; 
} 

void Rational::reduction()
{
    int largest; 

    largest = numerator > denominator ? numerator : denominator; 

    int gcd = 0; 

    for (int loop = 2; loop <= largest; loop  )
    {
        if (numerator % loop == 0 && denominator % loop == 0)
            gcd = loop; 

        if (gcd != 0)
        {
            numerator /= gcd; 
            denominator /= gcd; 
        } 

    }

}

this is the file I call the functions

#include <iostream>
using namespace std; 

#include "Rational.h" 

int main()
{
    Rational obj1(8, 14), obj2(5, 7), resobj; 

    obj1.printRational(); 
    cout << "   ";
    obj2.printRational(); 
    resobj = obj1.addition(obj2); 

    cout << " = "; 
    resobj.printRational(); 
    


}

CodePudding user response：

The proble is in void Rational::reduction() function.

What happens when if (numerator % loop == 0 && denominator % loop == 0) is false?

You should have initlise gcd to 0 for each iteration of for-loop or even batter, do't use gcd variable at all. See it here in action:

for (int loop = 2; loop <= largest; loop  )
{
    if (numerator % loop == 0 && denominator % loop == 0)
    {
        numerator /= loop; 
        denominator /= loop; 
    } 
}