您可以重定義或重載 C# 內建的運算子。因此,程式設計師也可以使用使用者自訂類型的運算子。重載運算子是具有特殊名稱的函數,是透過關鍵字 operator 後跟運算子的符號來定義的。與其他函數一樣,重載運算子有返回類型和參數列表。
例如,請看下面的函數:
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;}
上面的函數為使用者自訂的類別 Box 實作了加法運算子(+)。它把兩個 Box 物件的屬性相加,並傳回相加後的 Box 物件。
運算子重載的實作
下面的程式示範了完整的實作:
using System;namespace OperatorOvlApplication{ class Box { private double length; // 长度 privatedouble breadth; // 宽度 private double height; // 高度 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; } // 重载 + 运算符来把两个 Box 对象相加 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(); // 声明 Box1,类型为 Box Box Box2 = new Box(); // 声明 Box2,类型为 Box Box Box3 = new Box(); // 声明 Box3,类型为 Box double volume = 0.0; // 体积 // Box1 详述 Box1.setLength(6.0); Box1.setBreadth(7.0); Box1.setHeight(5.0); // Box2 详述 Box2.setLength(12.0); Box2.setBreadth(13.0); Box2.setHeight(10.0); // Box1 的体积 volume = Box1.getVolume(); Console.WriteLine("Box1 的体积: {0}", volume); // Box2 的体积 volume = Box2.getVolume(); Console.WriteLine("Box2 的体积: {0}", volume); // 把两个对象相加 Box3 = Box1 + Box2; // Box3 的体积 volume = Box3.getVolume(); Console.WriteLine("Box3 的体积: {0}", volume); Console.ReadKey(); } } }
當上面的程式碼被編譯和執行時,它會產生下列結果:
Box1 的体积: 210 Box2 的体积: 1560 Box3 的体积: 5400
可重載和不可重載運算子
下表描述了C# 中運算子重載的能力:描述 | |
+, -, *, /, % | |
==, !=, <, >, <=, >= | |
&&, || | |
+=, -=, *=, /=, %= | |
=, ., ?:, ->, new, is, sizeof, typeof | |
using System;namespace OperatorOvlApplication{ class Box { private double length; // 长度 privatedouble breadth; // 宽度 private double height; // 高度 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; } // 重载 + 运算符来把两个 Box 对象相加 public static Box operator+ (Box b, Box c) { Box box = newBox(); 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() { returnString.Format("({0}, {1}, {2})", length, breadth, height); } } class Tester { static void Main(string[] args) { Box Box1 = new Box(); // 声明 Box1,类型为 Box Box Box2 = new Box(); // 声明 Box2,类型为 Box Box Box3 = new Box(); // 声明 Box3,类型为 Box Box Box4 = new Box(); double volume = 0.0; // 体积 // Box1 详述 Box1.setLength(6.0); Box1.setBreadth(7.0); Box1.setHeight(5.0); // Box2 详述 Box2.setLength(12.0); Box2.setBreadth(13.0); Box2.setHeight(10.0); // 使用重载的 ToString() 显示两个盒子 Console.WriteLine("Box1: {0}", Box1.ToString()); Console.WriteLine("Box2: {0}", Box2.ToString()); // Box1 的体积 volume = Box1.getVolume(); Console.WriteLine("Box1 的体积: {0}", volume); // Box2 的体积 volume = Box2.getVolume(); Console.WriteLine("Box2 的体积: {0}", volume); // 把两个对象相加 Box3= Box1 + Box2; Console.WriteLine("Box3: {0}", Box3.ToString()); // Box3 的体积 volume =Box3.getVolume(); Console.WriteLine("Box3 的体积: {0}", volume); //comparing the boxes if (Box1 >Box2) Console.WriteLine("Box1 大于 Box2"); else Console.WriteLine("Box1 不大于 Box2"); if (Box1 <Box2) Console.WriteLine("Box1 小于 Box2"); else Console.WriteLine("Box1 不小于 Box2"); if (Box1>= Box2) Console.WriteLine("Box1 大于等于 Box2"); else Console.WriteLine("Box1 不大于等于 Box2"); if (Box1 <= Box2) Console.WriteLine("Box1 小于等于 Box2"); else Console.WriteLine("Box1 不小于等于 Box2"); if (Box1 != Box2) Console.WriteLine("Box1 不等于 Box2"); else Console.WriteLine("Box1 等于 Box2"); Box4 = Box3; if (Box3 == Box4) Console.WriteLine("Box3 等于 Box4"); else Console.WriteLine("Box3 不等于 Box4"); Console.ReadKey(); } } }
Box1: (6, 7, 5) Box2: (12, 13, 10) Box1 的体积: 210 Box2 的体积: 1560 Box3: (18, 20, 15) Box3 的体积: 5400 Box1 不大于 Box2 Box1 小于 Box2 Box1 不大于等于 Box2 Box1 小于等于 Box2 Box1 不等于 Box2 Box3 等于 Box4
rrreee
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