D Programming Examples

D Multi Level Inheritance

d

import std.stdio;

// Base class 
class Shape {
   public:
      void setWidth(int w) {
         width = w; 
      }

      void setHeight(int h) {
         height = h; 
      }

   protected: 
      int width; 
      int height; 
}

// Derived class 
class Rectangle: Shape {
   public:
      int getArea() {
         return (width * height); 
      }
}
 
class Square: Rectangle {
   this(int side) {
      this.setWidth(side); 
      this.setHeight(side); 
   }
}

void main() {
   Square square = new Square(13);

   // Print the area of the object.
   writeln("Total area: ", square.getArea());
}

D Base Classes and Derived Classes

d

import std.stdio;

// Base class 
class Shape { 
   public: 
      void setWidth(int w) { 
         width = w; 
      }

      void setHeight(int h) { 
         height = h; 
      }
   
   protected: 
      int width; 
      int height; 
}
  
// Derived class 
class Rectangle: Shape { 
   public: 
      int getArea() { 
         return (width * height); 
      } 
}
  
void main() { 
   Rectangle Rect = new Rectangle();
   
   Rect.setWidth(5); 
   Rect.setHeight(7); 
   
   // Print the area of the object. 
   writeln("Total area: ", Rect.getArea()); 
}

D Static Function Members

d

import std.stdio;

class Box { 
   public: 
      static int objectCount = 0; 
      
      // Constructor definition 
      this(double l = 2.0, double b = 2.0, double h = 2.0) { 
         writeln("Constructor called."); 
         length = l; 
         breadth = b; 
         height = h; 

         // Increase every time object is created 
         objectCount++; 
      }

      double Volume() {
         return length * breadth * height; 
      }

      static int getCount() { 
         return objectCount; 
      } 
   
   private: 
      double length;     // Length of a box 
      double breadth;    // Breadth of a box 
      double height;     // Height of a box 
};
  
void main() { 
   // Print total number of objects before creating object. 
   writeln("Inital Stage Count: ",Box.getCount());  
   
   Box Box1 = new Box(3.3, 1.2, 1.5);    // Declare box1 
   Box Box2 = new Box(8.5, 6.0, 2.0);    // Declare box2 
   
   // Print total number of objects after creating object. 
   writeln("Final Stage Count: ",Box.getCount()); 
}

D Static

d

import std.stdio;

class Box { 
   public: 
      static int objectCount = 0;

      // Constructor definition 
      this(double l = 2.0, double b = 2.0, double h = 2.0) { 
         writeln("Constructor called."); 
         length = l; 
         breadth = b; 
         height = h; 
          
         // Increase every time object is created
         objectCount++; 
      } 

      double Volume() { 
         return length * breadth * height; 
      }

   private: 
      double length;     // Length of a box 
      double breadth;    // Breadth of a box 
      double height;     // Height of a box 
};
  
void main() { 
   Box Box1 = new Box(3.3, 1.2, 1.5);    // Declare box1 
   Box Box2 = new Box(8.5, 6.0, 2.0);    // Declare box2  
   
   // Print total number of objects. 
   writeln("Total objects: ",Box.objectCount);  
}

D Pointer to classes

d

import std.stdio;

class Box { 
   public: 
      // Constructor definition 
      this(double l = 2.0, double b = 2.0, double h = 2.0) { 
         writeln("Constructor called."); 
         length = l; 
         breadth = b; 
         height = h; 
      }

      double Volume() { 
         return length * breadth * height; 
      } 

   private: 
      double length;     // Length of a box 
      double breadth;    // Breadth of a box 
      double height;     // Height of a box 
}

void main() { 
   Box Box1 = new Box(3.3, 1.2, 1.5);    // Declare box1 
   Box Box2 = new Box(8.5, 6.0, 2.0);    // Declare box2 
   Box *ptrBox;                // Declare pointer to a class.
   
   // Save the address of first object 
   ptrBox = &Box1; 
   
   // Now try to access a member using member access operator 
   writeln("Volume of Box1: ",ptrBox.Volume()); 
   
   // Save the address of first object 
   ptrBox = &Box2;  
   
   // Now try to access a member using member access operator 
   writeln("Volume of Box2: ", ptrBox.Volume()); 
}

D this pointer

d

import std.stdio;

class Box { 
   public: 
      // Constructor definition 
      this(double l = 2.0, double b = 2.0, double h = 2.0) { 
         writeln("Constructor called."); 
         length = l;
         breadth = b; 
         height = h; 
      }
         
      double Volume() { 
         return length * breadth * height; 
      }

      int compare(Box box) { 
         return this.Volume() > box.Volume(); 
      }

   private: 
      double length;     // Length of a box 
      double breadth;    // Breadth of a box 
      double height;     // Height of a box 
}
  
void main() { 
   Box Box1 = new Box(3.3, 1.2, 1.5);    // Declare box1 
   Box Box2 = new Box(8.5, 6.0, 2.0);    // Declare box2 
   
   if(Box1.compare(Box2)) { 
      writeln("Box2 is smaller than Box1"); 
   } else { 
      writeln("Box2 is equal to or larger than Box1"); 
   }
}

D Class Destructor

d

import std.stdio;

class Line { 
   public: 
      this() { 
         writeln("Object is being created"); 
      }

      ~this() { 
         writeln("Object is being deleted"); 
      } 

      void setLength( double len ) { 
         length = len; 
      } 

      double getLength() { 
         return length; 
      }
  
   private: 
      double length; 
}
  
// Main function for the program 
void main( ) { 
   Line line = new Line(); 
   
   // set line length 
   line.setLength(6.0); 
   writeln("Length of line : ", line.getLength()); 
}

D Parameterized Constructor

d

import std.stdio;

class Line { 
   public: 
      void setLength( double len ) { 
         length = len; 
      }
      double getLength() { 
         return length; 
      }
      this( double len) { 
         writeln("Object is being created, length = " , len ); 
         length = len; 
      } 

   private: 
      double length; 
} 
 
// Main function for the program 
void main( ) { 
   Line line = new Line(10.0);
   
   // get initially set length. 
   writeln("Length of line : ",line.getLength()); 
    
   // set line length again 
   line.setLength(6.0); 
   writeln("Length of line : ", line.getLength()); 
}

D Constructor

d

import std.stdio;

class Line { 
   public: 
      void setLength( double len ) {
         length = len; 
      }
      double getLength() { 
         return length; 
      }
      this() { 
         writeln("Object is being created"); 
      }

   private: 
      double length; 
} 
 
void main( ) { 
   Line line = new Line(); 
   
   // set line length 
   line.setLength(6.0); 
   writeln("Length of line : " , line.getLength()); 
}

D Class access modifiers

d

import std.stdio;

class Line { 
   public:
      double length; 

      double getLength() { 
         return length ; 
      }
      
      void setLength( double len ) { 
         length = len; 
      } 
} 
 
void main( ) { 
   Line line = new Line();
   
   // set line length 
   line.setLength(6.0); 
   writeln("Length of line : ", line.getLength());  
   
   // set line length without member function 
   line.length = 10.0; // OK: because length is public 
   writeln("Length of line : ", line.length); 
}

Follow

Newsletter