using System;
public class BaseClass
{protected string _className = "BaseClass";public virtual void PrintName(){Console.WriteLine("Class Name: {0}", _className);}
}
class DerivedClass : BaseClass
{public string _className = "DerivedClass";public override void PrintName(){Console.Write("The BaseClass Name is {0}");//调用基类方法base.PrintName();Console.WriteLine("This DerivedClass is {0}", _className);}
}
class TestApp
{public static void Main(){DerivedClass dc = new DerivedClass();dc.PrintName();}
}

// keywords_base2.cs
using System;
public class BaseClass
{int num;public BaseClass(){Console.WriteLine("in BaseClass()");}public BaseClass(int i){num = i;Console.WriteLine("in BaseClass(int {0})", num);}
}
public class DerivedClass : BaseClass
{// 该构造器调用  BaseClass.BaseClass()public DerivedClass(): base(){}// 该构造器调用 BaseClass.BaseClass(int i)public DerivedClass(int i): base(i){}static void Main(){DerivedClass dc = new DerivedClass();DerivedClass dc1 = new DerivedClass(1)();Console.ReadLine();}
}

// this 关键字
// keywords_this.cs
using System;
class Employee
{private string _name;private int _age;private string[] _arr = new string[5];public Employee(string name, int age){// 使用this限定字段，name与agethis._name = name;this._age = age;}public string Name{get { return this._name; }}public int Age{get { return this._age; }}// 打印雇员资料public void PrintEmployee(){// 将Employee对象作为参数传递到DoPrint方法Print.DoPrint(this);}// 声明索引器public string this[int param]{get { return _arr[param]; }set { _arr[param] = value; }}
}
class Print
{public static void DoPrint(Employee e){Console.WriteLine("Name: {0}\nAge: {1}", e.Name, e.Age);}
}
class TestApp
{static void Main(){Employee E = new Employee("Hunts", 21);E[0] = "Scott";E[1] = "Leigh";E[4] = "Kiwis";E.PrintEmployee();for (int i = 0; i < 5; i++){Console.WriteLine("Friends Name: {0}", E[i]);}Console.ReadLine();}
}