默认等于行为

Equals 在 Object 类中声明。

public virtual bool Equals(Object obj);

默认情况下，Equals 具有以下行为：

• 如果实例是引用类型，则 Equals 仅在引用相同时才返回 true。

• 如果实例是值类型，则 Equals 仅在类型和值相同时才返回 true。

• string 是一个特例。它的行为类似于值类型。

namespace ConsoleApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //areFooClassEqual: False
            Foo fooClass1 = new Foo("42");
            Foo fooClass2 = new Foo("42");
            bool areFooClassEqual = fooClass1.Equals(fooClass2);
            Console.WriteLine("fooClass1 and fooClass2 are equal: {0}", areFooClassEqual);
            //False

            //areFooIntEqual: True
            int fooInt1 = 42;
            int fooInt2 = 42;
            bool areFooIntEqual = fooInt1.Equals(fooInt2);
            Console.WriteLine("fooInt1 and fooInt2 are equal: {0}", areFooIntEqual);

            //areFooStringEqual: True
            string fooString1 = "42";
            string fooString2 = "42";
            bool areFooStringEqual = fooString1.Equals(fooString2);
            Console.WriteLine("fooString1 and fooString2 are equal: {0}", areFooStringEqual);
        }
    }

    public class Foo
    {
        public string Bar { get; }

        public Foo(string bar)
        {
            Bar = bar;
        }
    }
}