C# new Dictionary() is IDictionary 返回 false

Question

例子:

void Main()
{
    var dic = new Dictionary<string, object>();

    Console.WriteLine(dic is IDictionary<object, object>); //False
    Console.WriteLine(dic is IDictionary<dynamic, dynamic>); //False
    Console.WriteLine(dic is IDictionary<string, object>); //True
}

string 不也是一个对象吗？为什么 dic is IDictionary<object, object>得到假。

Answer 1

String派生自 Object .但是IDictionary<string, object>不源自 IDictionary<object, object> .这就是它返回 false 的原因。您可能想阅读 .NET 中的协变和逆变概念 https://learn.microsoft.com/en-us/dotnet/standard/generics/covariance-and-contravariance