//Ví dụ minh họa nạp chồng toán tử (operator) ==, !=, + , - trong C# sử dụng implicit và explicit

using System;

public class Fraction{

publicFraction(int numerator, int denominator){

     Console.WriteLine("In Fraction Constructor(int, int)");

     this.numerator=numerator;

     this.denominator=denominator;

}

publicFraction(int wholeNumber){

     Console.WriteLine("In Fraction Constructor(int)");

     numerator = wholeNumber;

     denominator = 1;

}

public static implicit operator Fraction(inttheInt){

     System.Console.WriteLine("In implicit conversion to Fraction");

     return new Fraction(theInt);

}

public static explicit operator int(Fraction theFraction){

     System.Console.WriteLine("In explicit conversion to int");

     returntheFraction.numerator / theFraction.denominator;

}

public static bool operator==(Fraction lhs, Fraction rhs){

     Console.WriteLine("In operator ==");

     if(lhs.denominator == rhs.denominator &&

         lhs.numerator == rhs.numerator)

     {

        return true;

     }

     // code here to handle unlike fractions

     return false;

}

public static bool operator !=(Fraction lhs, Fraction rhs){

     Console.WriteLine("In operator !=");

     return!(lhs==rhs);

}

public override bool Equals(object o){

     Console.WriteLine("In method Equals");

     if (! (o is Fraction) ){

        return false;

     }

     return this == (Fraction) o;

}

public static Fraction operator+(Fraction lhs, Fraction rhs){

     Console.WriteLine("In operator+");

     if(lhs.denominator == rhs.denominator){

        return new Fraction(lhs.numerator+rhs.numerator,

         lhs.denominator);

     }

     // simplistic solution for unlike fractions

     // 1/2 + 3/4 == (1*4) + (3*2) / (2*4) == 10/8

     intfirstProduct = lhs.numerator * rhs.denominator;

     intsecondProduct = rhs.numerator * lhs.denominator;

     return new Fraction(

        firstProduct + secondProduct,

        lhs.denominator * rhs.denominator

        );

}

public override stringToString(){

     String s = numerator.ToString( ) + "/" +

        denominator.ToString( );

     return s;

}

private int numerator;

private int denominator;

}

public class Tester{

static void Main(){

     //implicit conversion to Fraction

     Fraction f1 = newFraction(3);

     Console.WriteLine("f1: {0}", f1.ToString( ));

     Fraction f2 = newFraction(2,4);

     Console.WriteLine("f2: {0}", f2.ToString( ));

     Fraction f3 = f1 + f2;

     Console.WriteLine("f1 + f2 = f3: {0}", f3.ToString());

     Fraction f4 = f3 + 5;

     Console.WriteLine("f3 + 5 = f4: {0}", f4.ToString());

     Fraction f5 = newFraction(2,4);

     if (f5 == f2){

        Console.WriteLine("F5: {0} == F2: {1}", f5.ToString(),

       f2.ToString());

     }

     int k = (int)f4; //explicit conversion to int

     Console.WriteLine("int: F5 = {0}", k.ToString());

}

}