C#中的构造函数也可以应用方法重载。C#中有默认构造函数，也可以定义带参数的构造函数。构造函数必须与类同名，并且不能有返回值。所以C#构造函数重载相当于不同数量的参数方法重载。

using System;

class Animal

{

public string _name;

public string _color;

public int _speed;

public Animal()

{

    this._speed = 30;

}

public Animal(string name, string color)

{

    this._name = name;

    this._color = color;

}

public Animal(string name, string color, int speed)

{

    this._name = name;

    this._color = color;

    this._speed = speed;

}

}

class Program

{

static void Main(string[]args)

{

    //方法一

    Animal animal1 = new Animal();

    animal1._name = "兔子";

    animal1._color = "灰色";

    //animal1._speed = 40;

    Console.WriteLine(

      "调用默认构造函数输出动物为{0}，颜色为{1}，奔跑速度为{2}km/h",

    animal1._name, animal1._color, animal1._speed);

    //方法二

    Animal animal2 = new Animal("狗", "黄色");

    Console.WriteLine("调用两个参数构造函数输出动物为{0}，颜色为{1}",

      animal2._name, animal2._color);

    //方法三

    Animal animal3 = new Animal("花猫", "白色", 20);

    Console.WriteLine(

      "调用三个参数构造函数输出动物为{0},颜色为{1},奔跑速度为{2}",

      animal3._name, animal3._color, animal3._speed);

    Console.WriteLine("一只" + animal3._color + "的" + animal3._name + "正在以"

      + animal3._speed + "km/h的速度在奔跑\n");

    Console.ReadLine();

}

}

我们再看一个例子:

using System;

class Program

{

private string _name;

private int _age;

private string _qualification;

public Program()

{

    _age = 18;

}

public Program(string name, int age, string qualification)

{

    this._name = name;

    this._age = age;

    this._qualification = qualification;

}

static void Main()

{

    Program p = new Program();

    Console.WriteLine("默认构造函数输出年龄为" + p._age);

    Program p1 = new Program("李公", 19, "大学");

    Console.WriteLine("参数构造函数输出姓名为" + p1._name + "，年龄为" + p1._age

      + "，文化程度为" + p1._qualification);

}

}