C#集合與列表(一) -- 對象的統一性和對象的等值性

　　首先創建一個Person類.

Code
 public class Person
        {
                string FirstName;
                string LastName;

                public Person(string first, string last)
                {
                        FirstName = first;
                        LastName = last;
                }

                public string FullName
                {
                        get { return FirstName + " " + LastName; }
                }

}

Code
class Program
        {
                static void wl(string s)
                {
                        Console.WriteLine(s);
                }
                static void w(string s)
                {
                        Console.Write(s);
                }
                static void br()
                {
                        Console.WriteLine();
                }
                static void Main(string[] args)
                {                       
                        #region ArrayDemo
                        Person scott = new Person("Scott", "Hanselman");
                        Person bill = new Person("Bill", "Evjen");
                        Person srini = new Person("Srinivasa", "Sivakumar");

                        Person[] people ={ bill, scott, srini };

                        Console.WriteLine("We used foreach.");
                        foreach (Person p in people)
                        {
                                Console.WriteLine(p.FullName);
                        }
                        br();
                        Console.WriteLine("We used a for loop.");
                        {
                                for (int i = 0; i < people.Length; i++)
                                {
                                        Console.WriteLine(people[i].FullName);
                                }
                        }
                        br();

                        Person scott2 = new Person("Scott", "Hanselman");
                        int indexOfBill = Array.IndexOf(people, bill);
                        wl("Bill is at " + indexOfBill);
                        int indexOfScott = Array.IndexOf(people, scott);
                        wl("Scott is at " + indexOfScott);
                        int indexOfScott2 = Array.IndexOf(people, scott2);
                        wl("Scott2 is at " + indexOfScott2);

                        #endregion

                        Console.ReadKey();
                }
        }

執行結果如下:

雖然這兩個對象包含相同的至,但不是同一對象, 如果要獲取scott對象的索引,同時把scott2作為要搜索的對象,只需在Person類上提供一個Equals方法, 系統更可以使用該方法建立值相等的對象；

在Person類中重寫Equals方法之后的結果如下: 

Code
 public override bool Equals(object obj)
                {
                        Person other = obj as Person;
                        return (other.LastName == this.LastName && other.FirstName == this.FirstName);
                }

執行結果:

object.Equals方法與 object.ReferenceEquals說明:

object.Equals: 用于對象的等值性比較

object.ReferenceEquals: 用于對象的同一性比較 

CodePerson scott = new Person("Scott", "Hanselman");
                        Person bill = new Person("Bill", "Evjen");
                        Person srini = new Person("Srinivasa", "Sivakumar");

                        Person scott2 = new Person("Scott", "Hanselman");
                        int indexOfBill = Array.IndexOf(people, bill);
                        wl("Bill is at " + indexOfBill);
                        int indexOfScott = Array.IndexOf(people, scott);
                        wl("Scott is at " + indexOfScott);
                        int indexOfScott2 = Array.IndexOf(people, scott2);
                        wl("Scott2 is at " + indexOfScott2);
                        Person scott3 = scott2;

                        br();
                        wl("Equals " + object.Equals(scott, scott2).ToString());//對象等值性比較
                        wl("ReferenceEquals " + object.ReferenceEquals(scott, scott2));//對象同一性比較
                        #endregion