//程序7-8
using System;
class Reftest { public int testInt; }
class Student 
{
	public int studID;
	public string studName;
	public Reftest Ref1;
}

class CollegeStudent: Student 
{
	public int DepartmentID;

	// Main方法只有定義在派生類中才能直接調用MemberwiseClone方法。
	public static void Main() 
	{
		CollegeStudent S1 = new CollegeStudent();
		S1.studID = 2003179;
		S1.studName = "Sam";
		S1.DepartmentID=001;
		S1.Ref1 = new Reftest();
		S1.Ref1.testInt = 333;

		// 淺表副本創建與原始對象具有相同類型的新實例，然后復制原始對象的非靜態字段。
		// 如果字段是值類型的，則對該字段執行逐位復制。
		// 如果字段是引用類型，則復制該引用但不復制被引用的對象；
		// 這樣，原始對象中的引用和副本中的引用指向同一個對象。
		// 相反，對象的深層副本復制對象中字段直接或間接引用的全部內容。
		
		// Performs a shallow copy of m1 and assign it to m2.
		CollegeStudent S2 = (CollegeStudent)S1.MemberwiseClone();
		Console.WriteLine(S1.studID+"  "+S1.studName+" "+S1.DepartmentID+" "+S1.Ref1.testInt);
		Console.WriteLine(S2.studID+"  "+S2.studName+" "+S2.DepartmentID+" "+S2.Ref1.testInt);
		// 兩個對象本身
		Console.WriteLine(Object.ReferenceEquals(S1,S2)); // false
		Console.WriteLine(Object.Equals(S1,S2));          // false
		// 兩個對象數據成員中的值類型
		Console.WriteLine(Object.ReferenceEquals(S1.studID,S2.studID)); // false
		Console.WriteLine(Object.Equals(S1.studID,S2.studID));          // true
        // 兩個對象數據成員中的引用類型
		Console.WriteLine(Object.ReferenceEquals(S1.studName,S2.studName)); // true
		Console.WriteLine(Object.Equals(S1.studName,S2.studName));          // true
		Console.WriteLine(Object.ReferenceEquals(S1.Ref1,S2.Ref1)); // true
		Console.WriteLine(Object.Equals(S1.Ref1,S2.Ref1));          // true

	    Console.WriteLine("===================");
		S1.studName="Bush";
		// S1.studName="Sam";  // string類型是一個特殊的引用類型，只要字符串內容相同，則引用和值均相等
		S1.DepartmentID=002;
		S1.Ref1.testInt = 444;
		S1.studID = 2003180;
		Console.WriteLine(S1.studID+"  "+S1.studName+" "+S1.DepartmentID+" "+S1.Ref1.testInt);
		Console.WriteLine(S2.studID+"  "+S2.studName+" "+S2.DepartmentID+" "+S2.Ref1.testInt);
		// 兩個對象數據成員中的值類型
		Console.WriteLine(Object.ReferenceEquals(S1.studID,S2.studID)); // false
		Console.WriteLine(Object.Equals(S1.studID,S2.studID));          // true
		// 兩個對象數據成員中的引用類型
		Console.WriteLine(Object.ReferenceEquals(S1.studName,S2.studName)); // false
		Console.WriteLine(Object.Equals(S1.studName,S2.studName));          // false
		Console.WriteLine(Object.ReferenceEquals(S1.Ref1,S2.Ref1)); // true
		Console.WriteLine(Object.Equals(S1.Ref1,S2.Ref1));          // true

	}
}