Fractions class in c++ explaination [closed] - c++

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Can someone just explain whats going in this code? You don't have to go line by line but a general summary would be really helpful. It's similar to other fraction class c++ code so you don't have to completely refer to this code.
#include<iostream>
using namespace std;
class Fraction
{
private:
int num, den;
public:
Fraction(int n = 1, int d = 2) : num(n), den(d) { }
void show() { cout«num«”/”«den; }
Fraction operator+(Fraction f) const
{ return Fraction(num+f.num, den+f.den); }
Fraction operator-(Fraction f) const
{ return Fraction(num-f.num, den-f.den); }
Fraction operator*(Fraction f) const
{ return Fraction(num*f.num, den*f.den); }
Fraction operator/(Fraction f) const
{
int rNum = (f.den*num)/den;
return (rNum, f.num);
}
friend ostream& operator«(ostream& out, Fraction& f)
{ cout«f.num«”/”«f.den; return out; }
friend istream& operator»(istream& in, Fraction& f)
{ cout«”\nEnter Numerator: “; cin»f.num; cout«”Enter Denominator: “;
cin»f.den; cout«f.num«”/”«f.den; return in; }
int ndMax()
{ return (num<=den) ? num:den; }
void reduce()
{
for(int i = 2; i<=ndMax(); i++)
if(num%i == 0 && den%i == 0)
{ num = num/i; den = den/i; i = 1; }
}
}; //
int main()
{
Fraction f1(5, 6);
Fraction f2(80, 1001);
cout«f1«” and “«f2«endl;
Fraction f3 = f1/f2;
f3.reduce(); cout«f3;
cout«endl;
return 0;
}

Answer 1

// This declares a dependency on the system module, iostream. Specifically, this code uses the
// system provided objects, cout, and cin, for output and input.
#include <iostream>
// This says if the compiler cannot find a symbol, it should try looking in the namespace, std.
using namespace std;
// This defines a type called, Fraction.
class Fraction {
private:
// This declares two private member variables, num, and den, presumably representing the
// numerator and denominator of a fraction. Each object of type Fraction will have its own
// num and den. Because they are private they cannot be accidentally modified outside the
// definition of Fraction. They are the module's secret.
int num, den;
public:
// This declares a constructor. It uses the default argument notation to actually define
// three constructor syntaxes. Two arguments may be given, one, or zero. Fraction() = 1/2,
// Fraction(x) = x/2, and Fraction(x, y) = x/y. A default denominator of 1 would be more
// normal, especially since this constructor can be used to implicitly convert an int into
// a Fraction.
Fraction(int n = 1, int d = 2) : num(n), den(d) { }
// This function outputs a representation of a Fraction to cout. It repeats the definition
// of operator<< below, which violates the DRY principle so it should probably be written
// as: cout << *this;
void show() {
cout << num << " / " << den; }
// This is an operator overload. It allows you to write, Fraction + Fraction. Note that it
// does not add fractions in the expected way, instead it does a vector addition.
Fraction operator+(Fraction f) const {
return Fraction(num + f.num, den + f.den); }
// Similarly broken.
Fraction operator-(Fraction f) const {
return Fraction(num - f.num, den - f.den); }
// Correct multiplication, although normalizing the fraction is kind of expected.
Fraction operator*(Fraction f) const {
return Fraction(num * f.num, den * f.den); }
// Cannot be bothered to decide if this is correct. Multiplying by the inverse would be the
// more obvious thing to do, like: return *this * Fraction(f.den, f.num);
Fraction operator/(Fraction f) const {
int rNum = (f.den * num) / den;
return Fraction(rNum, f.num); }
// These functions support reading and writing a Fraction using streams. Note that they should
// make use of the out and in parameters, then they would work with all stream types.
friend ostream& operator<<(ostream& out, Fraction& f) {
cout << f.num << " / " << f.den;
return out; }
// The prompts here are poor design.
friend istream& operator>>(istream& in, Fraction& f) {
cout << "\nEnter Numerator: ";
cin >> f.num;
cout << "Enter Denominator: ";
cin >> f.den;
cout << f.num << " / " << f.den;
return in; }
// This function does not do what you would expect based on the name. It returns min(num, den).
// It should be declared const, like operator+ is since it is thread-safe.
int ndMax() {
return (num <= den) ? num : den; }
// This is weird and evil. The intent is to normalize the fraction. Euclid's algorithm would
// be the usual way.
void reduce() {
for (int i = 2; i <= ndMax(); i++)
if (num % i == 0 && den % i == 0) {
num = num / i;
den = den / i;
i = 1; // Evil!!! Do not modify the loop variable in the body of the loop.
} }
// There are a number of other functions, not explicit here, that are implicitly generated
// by the compiler. For example a copy constructor and assignment operator.
};
// This is a simple test driver for the Fraction class.
int main() {
Fraction f1(5, 6);
Fraction f2(80, 1001);
cout << f1 << " and " << f2 << endl;
Fraction f3 = f1 / f2;
f3.reduce();
cout << f3;
cout << endl;
return 0; }