C# Get from Hashtable, get object or reference

Question

当我们使用key从Hashtable获取一个对象时，我们得到一个引用的对象，即如果我们更改类的属性会影响Hashtable中的对象吗？

Answer 1

That will depend on whether the object is a reference or a value type. Example:

public class Foo
{
    public string Bar { get; set; }
}

public struct Baz
{
    public string Bazinga { get; set; }
}

class Program
{
    static void Main()
    {
        var hashtable1 = new Dictionary<string, Foo>
        {
            { "key1", new Foo { Bar = "old bar" } }
        };
        var hashtable2 = new Dictionary<string, Baz>
        {
            { "key1", new  Baz { Bazinga = "old bazinga" } }
        };

        var foo = hashtable1["key1"];
        foo.Bar = "new bar";
        var bar = hashtable2["key1"];
        bar.Bazinga = "new bazinga";

        Console.WriteLine(hashtable1["key1"].Bar);
        Console.WriteLine(hashtable2["key1"].Bazinga);
    }
}

prints:

new bar
old bazinga

Answer 2

Yes, if your object is a reference type ( class , not struct ).

Here is some code that proves it:

var ht = new Hashtable();
var o = new object();
ht["key"] = o;
Console.WriteLine(object.ReferenceEquals(o, ht["key"])); // == true