无涯教程-D语言 - 类静态方法函数让我们尝试以下示例以了解静态数据成员的概念- import std.stdio;

让我们尝试以下示例以了解静态数据成员的概念-

import std.stdio;
class Box {
public:
static int objectCount=0;
  </span><span class="com">//构造函数定义</span><span class="pln">
  </span><span class="kwd">this</span><span class="pun">(</span><span class="kwd">double</span><span class="pln"> l</span><span class="pun">=</span><span class="lit">2.0</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">double</span><span class="pln"> b</span><span class="pun">=</span><span class="lit">2.0</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">double</span><span class="pln"> h</span><span class="pun">=</span><span class="lit">2.0</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
     writeln</span><span class="pun">(</span><span class="str">"Constructor called."</span><span class="pun">);</span><span class="pln"> 
     length</span><span class="pun">=</span><span class="pln">l</span><span class="pun">;</span><span class="pln"> 
     breadth</span><span class="pun">=</span><span class="pln">b</span><span class="pun">;</span><span class="pln"> 
     height</span><span class="pun">=</span><span class="pln">h</span><span class="pun">;</span><span class="pln"> 
      
     </span><span class="com">//每次创建对象时增加</span><span class="pln">
     objectCount</span><span class="pun">++;</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln"> 

  </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">

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  
//打印对象总数。
writeln("Total objects: ",Box.objectCount);

}

编译并执行上述代码后，将产生以下输出-

Constructor called. 
Constructor called. 
Total objects: 2

静态函数

静态成员函数只能从类外部访问，让我们尝试以下示例以了解静态函数成员的概念-

import std.stdio;
class Box {
public:
static int objectCount=0;
  </span><span class="com">//构造函数定义</span><span class="pln">
  </span><span class="kwd">this</span><span class="pun">(</span><span class="kwd">double</span><span class="pln"> l</span><span class="pun">=</span><span class="lit">2.0</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">double</span><span class="pln"> b</span><span class="pun">=</span><span class="lit">2.0</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">double</span><span class="pln"> h</span><span class="pun">=</span><span class="lit">2.0</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
     writeln</span><span class="pun">(</span><span class="str">"Constructor called."</span><span class="pun">);</span><span class="pln"> 
     length</span><span class="pun">=</span><span class="pln">l</span><span class="pun">;</span><span class="pln"> 
     breadth</span><span class="pun">=</span><span class="pln">b</span><span class="pun">;</span><span class="pln"> 
     height</span><span class="pun">=</span><span class="pln">h</span><span class="pun">;</span><span class="pln"> 

     </span><span class="com">//每次创建对象时增加</span><span class="pln">
     objectCount</span><span class="pun">++;</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln">

  </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">static</span><span class="pln"> </span><span class="kwd">int</span><span class="pln"> getCount</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"> objectCount</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() {
//在创建对象之前打印对象总数。
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 
//创建对象后打印对象总数。
writeln("Final Stage Count: ",Box.getCount());
}

编译并执行上述代码后，将产生以下输出-

Inital Stage Count: 0 
Constructor called. 
Constructor called
Final Stage Count: 2

无涯教程-D语言 - 类静态方法函数

静态函数

参考链接