在D中每个对象都有通过一个名为this指针,这个指针访问它自己的地址。this 指针是一个隐含的参数，所有的成员函数。因此，一个成员函数内，this 可以用来指调用对象。
让我们试试下面的例子就明白了this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; |
| } |
| 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"); |
| } |
| } |
Constructor called. Constructor called. Box2 is equal to or larger than Box1
