C# operator overloading

You can redefine or overload operators built into C#. Therefore, programmers can also use operators of user-defined types. An overloaded operator is a function with a special name, defined by the keyword operator followed by the symbol of the operator. Like other functions, overloaded operators have a return type and parameter list.

For example, consider the following function:

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;}

The above function implements the addition operator (+) for the user-defined class Box. It adds the properties of two Box objects and returns the added Box object.

Implementation of operator overloading

The following program demonstrates the complete implementation:

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();      
 }   
 }
 }

When the above code is compiled and executed, it produces the following results:

Box1 的体积： 210 Box2 的体积： 1560 Box3 的体积： 5400

Overloadable and non-overloadable operators

The following table describes the capabilities of operator overloading in C#:

##OperatorDescription+, -, !, ~, ++, --These unary operators have only one operand and can be overloaded . +, -, *, /, %These binary operators take two operands and can be overloaded. ##==, !=, <, >, <=, >=&&, ||+=, -=, *=, /=, %==, ., ?:, ->, new, is, sizeof, typeofExample

These comparison operators can be overloaded
These conditional logical operators cannot be directly overloaded.
These assignment operators cannot be overloaded.
These operators cannot be overloaded.

In view of the above discussion, let us extend the above example and overload more operators:

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();      
    }    
    }
    }

When the above When the code is compiled and executed, it will produce the following results:

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

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