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類指針

一個指向類是做完全相同的方式作為一個指向結構和存取指針的成員使用成員訪問運算符類- >操作符,就像結構體指針。與其它的指針一樣,必須在使用前初始化指針。

讓我們試試下麵的例子就明白了指針指向一個類的概念:

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 yiibaier 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());
}

讓我們編譯和運行上麵的程序,這將產生以下結果:

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