Wednesday 5 October 2016

19. Operator Overloading C# (Basic/Dasar)

Operator Overloading adalah melakukan overload pada built in method yang ada pada C#. Sehingga programmer dapat mendefinisikan operator berdasarkan tipe data yang didefinisikan dalam hal ini adalah class atau object.

Berikut adalah contoh bagaimana overloading pada operator +:

public static Box operator+ (Box b, Box c)
{
   Box box = new Box();
   box.length = b.length + c.length;
   box.breadth = b.breadth + c.breadth;
   box.height = b.height + c.height;
   return box;
}

Pada contoh diatas kita melakukan overloading pada operator +, jika ada operasi penambahan antar class box.

Implementasi Operator Overloading

Contoh di bawah ini mengilustrasikan operator overloading:

using System;
namespace OperatorOvlApplication
{
   class Box
   {
      private double length;   // Length of a box
      private double breadth;  // Breadth of a box
      private double height;   // Height of a box

      public double getVolume()
      {
         return length * breadth * height;
      }
      
      public void setLength( double len )
      {
         length = len;
      }

      public void setBreadth( double bre )
      {
         breadth = bre;
      }

      public void setHeight( double hei )
      {
         height = hei;
      }
      
      // Overload + operator to add two Box objects.
      public static Box operator+ (Box b, Box c)
      {
         Box box = new Box();
         box.length = b.length + c.length;
         box.breadth = b.breadth + c.breadth;
         box.height = b.height + c.height;
         return box;
      }

   }

   class Tester
   {
      static void Main(string[] args)
      {
         Box Box1 = new Box();   // Declare Box1 of type Box
         Box Box2 = new Box();   // Declare Box2 of type Box
         Box Box3 = new Box();   // Declare Box3 of type Box
         double volume = 0.0;    // Store the volume of a box here

         // box 1 specification
         Box1.setLength(6.0);
         Box1.setBreadth(7.0);
         Box1.setHeight(5.0);

         // box 2 specification
         Box2.setLength(12.0);
         Box2.setBreadth(13.0);
         Box2.setHeight(10.0);

         // volume of box 1
         volume = Box1.getVolume();
         Console.WriteLine("Volume of Box1 : {0}", volume);

         // volume of box 2
         volume = Box2.getVolume();
         Console.WriteLine("Volume of Box2 : {0}", volume);

         // Add two object as follows:
         Box3 = Box1 + Box2;

         // volume of box 3
         volume = Box3.getVolume();
         Console.WriteLine("Volume of Box3 : {0}", volume);
         Console.ReadKey();
      }
   }
}

Dari contoh di atas bisa kita ketahui kalau ingin mendefinisikan operator overloading adalah dengan menggunakan keyword operator kemudian diikuti dengain simbol operator yang ingin dioverload/dioverride. Misalnya kita ingin melakukan overloading pada operator * maka bisa kita denfinisikan denga cara:

public static ClassName operator* (ClassName a, ClassName b)
{
   // do operation here
}

Dari contoh program di atas jika dijalankan akan memberikan output sebagai berikut:

Volume of Box1 : 210
Volume of Box2 : 1560
Volume of Box3 : 5400

Berikut adalah daftar table operator apa saja yang bisa dioverload/dioverride pada C# dan mungkin akan sedikit berbeda dengan bahasa pemrograman yang lain:

OperatorsDescription
+, -, !, ~, ++, --These unary operators take one operand and can be overloaded.
+, -, *, /, %These binary operators take one operand and can be overloaded.
==, !=, <, >, <=, >=The comparison operators can be overloaded
&&, ||The conditional logical operators cannot be overloaded directly.
+=, -=, *=, /=, %=The assignment operators cannot be overloaded.
=, ., ?:, ->, new, is, sizeof, typeofThese operators cannot be overloaded.

Berikut adalah contoh agar kita semakin jelas dengan operator overloading:

using System;
namespace OperatorOvlApplication
{
   class Box
   {
      private double length;    // Length of a box
      private double breadth;   // Breadth of a box
      private double height;    // Height of a box
      
      public double getVolume()
      {
         return length * breadth * height;
      }
      
      public void setLength( double len )
      {
         length = len;
      }
      
      public void setBreadth( double bre )
      {
         breadth = bre;
      }
      
      
      public void setHeight( double hei )
      {
         height = hei;
      }
      
      // Overload + operator to add two Box objects.
      public static Box operator+ (Box b, Box c)
      {
         Box box = new Box();
         box.length = b.length + c.length;
         box.breadth = b.breadth + c.breadth;
         box.height = b.height + c.height;
         return box;
      }
      
      public static bool operator == (Box lhs, Box rhs)
      {
         bool status = false;
         if (lhs.length == rhs.length && lhs.height == rhs.height && lhs.breadth == rhs.breadth)
         {
            status = true;
         }
         return status;
      }
      
      public static bool operator !=(Box lhs, Box rhs)
      {
         bool status = false;
         if (lhs.length != rhs.length || lhs.height != rhs.height || lhs.breadth != rhs.breadth)
         {
            status = true;
         }
         return status;
      }
      
      public static bool operator <(Box lhs, Box rhs)
      {
         bool status = false;
         if (lhs.length < rhs.length && lhs.height < rhs.height && lhs.breadth < rhs.breadth)
         {
            status = true;
         }
         return status;
      }
      
      public static bool operator >(Box lhs, Box rhs)
      {
         bool status = false;
         if (lhs.length > rhs.length && lhs.height > rhs.height && lhs.breadth > rhs.breadth)
         {
            status = true;
         }
         return status;
      }
      
      public static bool operator <=(Box lhs, Box rhs)
      {
         bool status = false;
         if (lhs.length <= rhs.length && lhs.height <= rhs.height && lhs.breadth <= rhs.breadth)
         {
            status = true;
         }
         return status;
      }
      
      public static bool operator >=(Box lhs, Box rhs)
      {
         bool status = false;
         if (lhs.length >= rhs.length && lhs.height >= rhs.height && lhs.breadth >= rhs.breadth)
         {
            status = true;
         }
         return status;
      }
      public override string ToString()
      {
         return String.Format("({0}, {1}, {2})", length, breadth, height);
      }
   }
   
   class Tester
   {
      static void Main(string[] args)
      {
         Box Box1 = new Box();   // Declare Box1 of type Box
         Box Box2 = new Box();   // Declare Box2 of type Box
         Box Box3 = new Box();   // Declare Box3 of type Box
         Box Box4 = new Box();
         double volume = 0.0;    // Store the volume of a box here
         
         // box 1 specification
         Box1.setLength(6.0);
         Box1.setBreadth(7.0);
         Box1.setHeight(5.0);
         
         // box 2 specification
         Box2.setLength(12.0);
         Box2.setBreadth(13.0);
         Box2.setHeight(10.0);
         
         //displaying the Boxes using the overloaded ToString():
         Console.WriteLine("Box 1: {0}", Box1.ToString());
         Console.WriteLine("Box 2: {0}", Box2.ToString());
         
         // volume of box 1
         volume = Box1.getVolume();
         Console.WriteLine("Volume of Box1 : {0}", volume);
         
         // volume of box 2
         volume = Box2.getVolume();
         Console.WriteLine("Volume of Box2 : {0}", volume);
         
         // Add two object as follows:
         Box3 = Box1 + Box2;
         Console.WriteLine("Box 3: {0}", Box3.ToString());
         
         // volume of box 3
         volume = Box3.getVolume();
         Console.WriteLine("Volume of Box3 : {0}", volume);
         
         //comparing the boxes
         if (Box1 > Box2)
            Console.WriteLine("Box1 is greater than Box2");
         else
            Console.WriteLine("Box1 is  greater than Box2");
         
         if (Box1 < Box2)
            Console.WriteLine("Box1 is less than Box2");
         else
            Console.WriteLine("Box1 is not less than Box2");
         
         if (Box1 >= Box2)
            Console.WriteLine("Box1 is greater or equal to Box2");
         else
            Console.WriteLine("Box1 is not greater or equal to Box2");
         
         if (Box1 <= Box2)
            Console.WriteLine("Box1 is less or equal to Box2");
         else
            Console.WriteLine("Box1 is not less or equal to Box2");
         
         if (Box1 != Box2)
            Console.WriteLine("Box1 is not equal to Box2");
         else
            Console.WriteLine("Box1 is not greater or equal to Box2");
         Box4 = Box3;
         
         if (Box3 == Box4)
            Console.WriteLine("Box3 is equal to Box4");
         else
            Console.WriteLine("Box3 is not equal to Box4");
         
         Console.ReadKey();
      }
   }
}

Setelah program dijalankan akan memberikan hasil sebagai berikut:

Box 1: (6, 7, 5)
Box 2: (12, 13, 10)
Volume of Box1 : 210
Volume of Box2 : 1560
Box 3: (18, 20, 15)
Volume of Box3 : 5400
Box1 is not greater than Box2
Box1 is less than Box2
Box1 is not greater or equal to Box2
Box1 is less or equal to Box2
Box1 is not equal to Box2
Box3 is equal to Box4

Ok guys gampang kan? sampai ketemu di tutorial selanjutnya Interface.

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