无涯教程-D语言 - 重载重载指与其它函数具有相同的函数名，但参数不相同的函数实现。函数重载在同一个作用域中，可以

重载指与其它函数具有相同的函数名，但参数不相同的函数实现。

函数重载

在同一个作用域中，可以为同一个函数名具有多个定义。函数的定义必须在参数列表中的参数类型/数量上彼此不同。

以下示例使用相同的函数 print()打印不同的数据类型-

import std.stdio; 
import std.string; 
class printData {
public:
void print(int i) {
writeln("Printing int: ",i);
}
  </span><span class="kwd">void</span><span class="pln"> </span><span class="kwd">print</span><span class="pun">(</span><span class="kwd">double</span><span class="pln"> f</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">"Printing float: "</span><span class="pun">,</span><span class="pln">f </span><span class="pun">);</span><span class="pln">
  </span><span class="pun">}</span><span class="pln">

  </span><span class="kwd">void</span><span class="pln"> </span><span class="kwd">print</span><span class="pun">(</span><span class="kwd">string</span><span class="pln"> s</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">"Printing string: "</span><span class="pun">,</span><span class="pln">s</span><span class="pun">);</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln"> 

};
void main() {
printData pd=new printData();
//调用 print 打印整数
pd.print(5);
//调用 print 打印浮点数
pd.print(500.263);
//调用print打印字符
pd.print("Hello Learnfk");
}

编译并执行上述代码后，将产生以下输出-

Printing int: 5 
Printing float: 500.263 
Printing string: Hello Learnfk

运算符重载

您可以重新定义或重载D中可用的大多数内置运算符。

可以根据正在重载的运算符，使用字符串op紧随其后的Add，Sub等来重载运算符，我们可以使运算符+重载以添加两个框，如下所示。

Box opAdd(Box b) { 
   Box box=new Box(); 
   box.length=this.length + b.length; 
   box.breadth=this.breadth + b.breadth; 
   box.height=this.height + b.height; 
   return box; 
}

对象作为参数传递，其属性可以使用该对象访问，可以使用 this 运算符访问调用该运算符的对象，如下所述-

import std.stdio;
class Box {
public:

double getVolume() {
return length  breadth  height;
}
  </span><span class="kwd">void</span><span class="pln"> setLength</span><span class="pun">(</span><span class="pln"> </span><span class="kwd">double</span><span class="pln"> len </span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
     length</span><span class="pun">=</span><span class="pln">len</span><span class="pun">;</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln"> 

  </span><span class="kwd">void</span><span class="pln"> setBreadth</span><span class="pun">(</span><span class="pln"> </span><span class="kwd">double</span><span class="pln"> bre </span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
     breadth</span><span class="pun">=</span><span class="pln">bre</span><span class="pun">;</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln">

  </span><span class="kwd">void</span><span class="pln"> setHeight</span><span class="pun">(</span><span class="pln"> </span><span class="kwd">double</span><span class="pln"> hei </span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
     height</span><span class="pun">=</span><span class="pln">hei</span><span class="pun">;</span><span class="pln"> 
  </span><span class="pun">}</span><span class="pln">

  </span><span class="typ">Box</span><span class="pln"> opAdd</span><span class="pun">(</span><span class="typ">Box</span><span class="pln"> b</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln"> 
     </span><span class="typ">Box</span><span class="pln"> box</span><span class="pun">=</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Box</span><span class="pun">();</span><span class="pln"> 
     box</span><span class="pun">.</span><span class="pln">length</span><span class="pun">=</span><span class="kwd">this</span><span class="pun">.</span><span class="pln">length </span><span class="pun">+</span><span class="pln"> b</span><span class="pun">.</span><span class="pln">length</span><span class="pun">;</span><span class="pln"> 
     box</span><span class="pun">.</span><span class="pln">breadth</span><span class="pun">=</span><span class="kwd">this</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">breadth</span><span class="pun">;</span><span class="pln"> 
     box</span><span class="pun">.</span><span class="pln">height</span><span class="pun">=</span><span class="kwd">this</span><span class="pun">.</span><span class="pln">height </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"> 
     </span><span class="kwd">return</span><span class="pln"> box</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
};
//主函数
void main( ) {
Box box1=new Box();    //实例化box1
Box box2=new Box();    
Box box3=new Box();    
double volume=0.0;     //存储体积变量
//box1赋值
box1.setLength(6.0);
box1.setBreadth(7.0);
box1.setHeight(5.0);
//box2赋值
box2.setLength(12.0);
box2.setBreadth(13.0);
box2.setHeight(10.0);
//box1体积
volume=box1.getVolume();
writeln("Volume of Box1 : ", volume);
//box2体积
volume=box2.getVolume();
writeln("Volume of Box2 : ", volume);
//添加两个对象如下：
box3=box1 + box2;
//volume of box 3 
volume=box3.getVolume();
writeln("Volume of Box3 : ", volume);

}

编译并执行上述代码后，将产生以下输出-

Volume of Box1 : 210 
Volume of Box2 : 1560 
Volume of Box3 : 5400

无涯教程-D语言 - 重载

函数重载

运算符重载

参考链接