C# – Operator Overloading
Kamu bisa mengubah ulang atau overload sebagian besar operator bawaan yang tersedia di C#. Jadi seorang programmer bisa menggunakan operator dengan tipe data yang ditentukan sendiri juga. Operator yang di-overload adalah fungsi dengan nama khusus yang diawali dengan kata kunci operator diikuti dengan simbol operator yang ingin didefinisikan. Seperti halnya fungsi lainnya, overloaded operator memiliki tipe pengembalian dan daftar parameter.
Misalnya, coba baca fungsi berikut ini:
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;
}Fungsi di atas mengimplementasikan operator penjumlahan (+) untuk kelas Box yang ditentukan oleh pengguna. Fungsi ini menjumlahkan atribut-atribut dari dua objek Box dan mengembalikan objek Box hasilnya.
Implementing the Operator Overloading
Program berikut ini menunjukkan implementasi lengkapnya:
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();
}
}
}Ketika kode di atas di-compile dan dijalankan, hasilnya bakal muncul seperti ini:
Volume of Box1 : 210
Volume of Box2 : 1560
Volume of Box3 : 5400Overloadable and Non-Overloadable Operators
Tabel berikut ini menjelaskan kemampuan overload operator dalam C#:
| Sr.No. | Operators & Description |
|---|---|
| 1 | +, -, !, ~, ++, — Operator unary ini ngambil satu operand dan bisa di-overload. |
| 2 | +, -, *, /, % Operator biner ini ngambil satu operand dan bisa di-overload. |
| 3 | ==, !=, <, >, <=, >= Operator pembanding ini bisa di-overload. |
| 4 | &&, || Operator logika kondisional ini nggak bisa di-overload langsung. |
| 5 | +=, -=, *=, /=, %= Operator penugasan ini nggak bisa di-overload. |
| 6 | =, ., ?:, ->, new, is, sizeof, typeof Operator-operator ini nggak bisa di-overload. |
Contoh:
Berdasarkan pembahasan di atas, mari kita perluas contoh sebelumnya dan overload beberapa operator tambahan:
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 not 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();
}
}
}Ketika kode di atas di-compile dan dijalankan, hasilnya bakal muncul seperti ini:
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