D编程 Pointer to D classes

指向D语言类指针的方式与指向结构指针以及访问类指针的成员的方式完全相同，您可以使用成员访问运算符->运算符，就如同对结构的指针一样。同样，与所有指针一样，您必须在使用指针之前对其进行初始化。

让我们尝试以下示例，以了解指向类的指针的概念-

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()); 
} 

编译并执行上述代码后，将产生以下输出-

Constructor called. 
Constructor called. 
Volume of Box1: 5.94 
Volume of Box2: 102