Binary Operators Overloading

The following table shows the list of binary operators and its purpose.

An example is shown below which explains how to overload an binary operator.

Example

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 opBinary(string op)(Box b) { 
         if(op == "+") { 
            Box box = new Box(); 
            box.length = this.length + b.length; 
            box.breadth = this.breadth + b.breadth; 
            box.height = this.height + b.height; 
            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 
   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(); 
   writeln("Volume of Box1 : ", volume);
   
   // volume of box 2 
   volume = box2.getVolume(); 
   writeln("Volume of Box2 : ", volume);
   
   // Add two object as follows: 
   box3 = box1 + box2;
   
   // volume of box 3 
   volume = box3.getVolume(); 
   writeln("Volume of Box3 : ", volume); 
}

When the above code is compiled and executed, it produces the following result −

Volume of Box1 : 210 
Volume of Box2 : 1560 
Volume of Box3 : 5400