Unary Operators 重载

下表显示了一元运算符列表及其用途。

下面显示了一个示例，它解释了如何重载二元运算符。

import std.stdio;
class Box { 
   public:  
      double getVolume() { 
         return length * breadth * height; 
      }
      void setLength( double len ) { 
         length = len; 
      }
      void setBreadth( double bre ) { 
         breadth = bre; 
      }
      void setHeight( double hei ) { 
         height = hei; 
      }
      Box opUnary(string op)() { 
         if(op == "++") { 
            Box box = new Box(); 
            box.length = this.length + 1; 
            box.breadth = this.breadth + 1 ; 
            box.height = this.height + 1; 
            return box; 
         }
      }
   private: 
      double length;      // Length of a box 
      double breadth;     // Breadth of a box 
      double height;      // Height of a box 
}; 
// Main function for the program 
void main( ) { 
   Box Box1 = new Box();    // Declare Box1 of type Box 
   Box Box2 = new Box();    // Declare Box2 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);
   // volume of box 1 
   volume = Box1.getVolume(); 
   writeln("Volume of Box1 : ", volume); 
   // Add two object as follows: 
   Box2 = ++Box1;
   // volume of box2 
   volume = Box2.getVolume(); 
   writeln("Volume of Box2 : ", volume);  
}

编译并执行上述代码时，会产生以下结果 -

Volume of Box1 : 210 
Volume of Box2 : 336