C# Equals

【C# Equals】

1、Object.Equals()

　　The type of comparison between the current instance and the obj parameter depends on whether the current instance is a reference type or a value type.

　　If the current instance is a reference type, the Equals(Object) method tests for reference equality, and a call to the Equals(Object) method is equivalent to a call to the ReferenceEquals method. Reference equality means that the object variables that are compared refer to the same object.

using System;

// Define a reference type that does not override Equals.
public class Person
{
   private string personName;

   public Person(string name)
   {
      this.personName = name;
   }

   public override string ToString()
   {
      return this.personName;
   }
}

public class Example
{
   public static void Main()
   {
      Person person1a = new Person("John");
      Person person1b = person1a;
      Person person2 = new Person(person1a.ToString());

      Console.WriteLine("Calling Equals:");
      Console.WriteLine("person1a and person1b: {0}", person1a.Equals(person1b));
      Console.WriteLine("person1a and person2: {0}", person1a.Equals(person2));  

      Console.WriteLine("\nCasting to an Object and calling Equals:");
      Console.WriteLine("person1a and person1b: {0}", ((object) person1a).Equals((object) person1b));
      Console.WriteLine("person1a and person2: {0}", ((object) person1a).Equals((object) person2));
   }
}
// The example displays the following output:
//       person1a and person1b: True
//       person1a and person2: False
//
//       Casting to an Object and calling Equals:
//       person1a and person1b: True
//       person1a and person2: False

　

2、ValueType.Equals()

　　比较两个值是否相等。

参考：

1、http://msdn.microsoft.com/zh-cn/library/bsc2ak47(v=vs.110).aspx

2、http://msdn.microsoft.com/zh-cn/library/2dts52z7(v=vs.110).aspx