# 重載

D編程允許爲一個函數名或在相同的範圍內操作，這就是所謂的函數重載和運算符重載分別指定一個以上的定義。

## 函數重載

import std.stdio; import std.string; class printData { public: void print(int i) { writeln("Printing int: ",i); } void print(double f) { writeln("Printing float: ",f ); } void print(string s) { writeln("Printing string: ",s); } }; void main() { printData pd = new printData(); // Call print to print integer pd.print(5); // Call print to print float pd.print(500.263); // Call print to print character pd.print("Hello D"); }

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

## 運算符重載

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; }

import std.stdio; class Box { public: double getVolume() { return length * breadth * height; } void setLength( double len ) { length = len; } void setBreadth( double bre ) { breadth = bre; } void setHeight( double hei ) { height = hei; } 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; } private: double length; // Length of a box double breadth; // Breadth of a box double height; // Height of a box }; // Main function for the program void main( ) { Box box1 = new Box(); // Declare box1 of type Box Box box2 = new Box(); // Declare box2 of type Box Box box3 = new Box(); // Declare box3 of type Box double volume = 0.0; // Store the volume of a box here // box 1 specification box1.setLength(6.0); box1.setBreadth(7.0); box1.setHeight(5.0); // box 2 specification box2.setLength(12.0); box2.setBreadth(13.0); box2.setHeight(10.0); // volume of box 1 volume = box1.getVolume(); writeln("Volume of Box1 : ", volume); // volume of box 2 volume = box2.getVolume(); writeln("Volume of Box2 : ", volume); // Add two object as follows: box3 = box1 + box2; // volume of box 3 volume = box3.getVolume(); writeln("Volume of Box3 : ", volume); }

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

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