D语言中的每个对象都可以通 this 访问自己的指针地址， this 指针是所有成员函数的隐式参数。
让我们尝试以下示例以了解 this 指针的概念-
import std.stdio;
class Box {
public:
//构造函数定义
this(double l=2.0, double b=2.0, double h=2.0) {
writeln("Constructor called.");
length=l;
breadth=b;
height=h;
}
</span><span class="kwd">double</span><span class="pln"> </span><span class="typ">Volume</span><span class="pun">()</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
</span><span class="kwd">return</span><span class="pln"> length </span><span class="pun">*</span><span class="pln"> breadth </span><span class="pun">*</span><span class="pln"> height</span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span><span class="pln">
</span><span class="kwd">int</span><span class="pln"> compare</span><span class="pun">(</span><span class="typ">Box</span><span class="pln"> box</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
</span><span class="kwd">return</span><span class="pln"> </span><span class="kwd">this</span><span class="pun">.</span><span class="typ">Volume</span><span class="pun">()</span><span class="pln"> </span><span class="pun">></span><span class="pln"> box</span><span class="pun">.</span><span class="typ">Volume</span><span class="pun">();</span><span class="pln">
</span><span class="pun">}</span><span class="pln">
private:
double length; //长
double breadth; //宽
double height; //高
}
void main() {
Box Box1=new Box(3.3, 1.2, 1.5); //实例化box1
Box Box2=new Box(8.5, 6.0, 2.0); //实例化box2
if(Box1.compare(Box2)) {
writeln("Box2 is smaller than Box1");
} else {
writeln("Box2 is equal to or larger than Box1");
}
}
编译并执行上述代码后，将产生以下输出-
Constructor called. Constructor called. Box2 is equal to or larger than Box1
