- C# 基础教程
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- C# - 运算符重载
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C# - 运算符重载
您可以重新定义或重载 C# 中可用的大多数内置运算符。因此,程序员也可以将运算符与用户定义的类型一起使用。重载运算符是具有特殊名称的函数,关键字运算符后跟所定义的运算符的符号。与任何其他函数类似,重载运算符具有返回类型和参数列表。
例如,执行以下函数 -
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; }
上面的函数为用户定义的类 Box 实现了加法运算符 (+)。它将两个 Box 对象的属性相加并返回结果 Box 对象。
实现运算符重载
以下程序显示了完整的实现 -
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(); } } }
当上面的代码被编译并执行时,它会产生以下结果 -
Volume of Box1 : 210 Volume of Box2 : 1560 Volume of Box3 : 5400
可重载和不可重载运算符
下表描述了 C# 中运算符的重载能力 -
先生。 | 运算符和描述 |
---|---|
1 | +、-、!、~、++、-- 这些一元运算符采用一个操作数并且可以重载。 |
2 | +、-、*、/、% 这些二元运算符采用一个操作数并且可以重载。 |
3 | ==、!=、<、>、<=、>= 比较运算符可以重载。 |
4 | &&,|| 条件逻辑运算符不能直接重载。 |
5 | +=、-=、*=、/=、%= 赋值运算符不能重载。 |
6 | =, ., ?:, ->, new, is, sizeof, typeof 这些运算符不能重载。 |
例子
根据上述讨论,让我们扩展前面的示例,并重载更多的运算符 -
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(); } } }
当上面的代码被编译并执行时,它会产生以下结果 -
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