面向对象（六）-派生类的构造函数

派生类的构造函数

• 语法

 public DerivedClass ():base(){}

如果不显式声明调用父类的无参构造函数（base()），那么默认会调用父类的无参构造函数。

• 无参Example

 class BaseClass
    {
        public BaseClass() {
            Console.WriteLine("BaseClass");
        }
    }

class DerivedClass:BaseClass
    {
        public DerivedClass ():base() { // 因为是无参数，所以`:base()`默认可以不写
            Console.WriteLine("DerivedClass");
        } 
    }

class Program
    {
        static void Main(string[] args)
        {
            DerivedClass derived = new DerivedClass();
            // 先调用base的构造方法，再调用子类的构造方法

            Console.ReadKey();
        }
    }

• 有参数Example

class BaseClass
    {
        private int x;
        public BaseClass() {
            Console.WriteLine("BaseClass");
        }
        public BaseClass(int x) {
            this.x = x;
        }
    }

class DerivedClass:BaseClass 
 {
        private int y;
        public DerivedClass ():base() {
            Console.WriteLine("DerivedClass");
        }
        public DerivedClass(int x, int y) : base(x) { // `base中的x就是前面的x`
            this.y = y;
            Console.WriteLine("x=" + x + ",  y=" + y);
        }
 }

class Program
    {
        static void Main(string[] args)
        {

            DerivedClass initDerived = new DerivedClass(5, 10);

            Console.ReadKey();
        }
    }

• 代码来源：
  作者：silence_k
  链接：http://www.jianshu.com/p/144ca89cc5e2
  來源：简书