c# "is" comparison with type stored in variable --

Question

I want to change the type with which I am comparing in an "is" statement at runtime, which I believe is not possible with "is" if i understand this Q&A right But I don't fully understand the answer given there,

could somebody please give an example on how to make a working type comparison with a changeable type ?

Similar to what I have tried here : //does not work (at least not with my c# ;-) )

    public static Type T;

    public class A { }
    public class B { }

    public static void Main(string[] args)
    {

        A AObject = new A();

        T = typeof(A);

        Console.WriteLine(AObject is T); // schould print true if it worked

        T = typeof(B);

        Console.WriteLine(AObject is T); // should print false if it worked

        Console.Read();
    }

The Question linked as Reason for closing this one is not considered a good on topic question I agree with that, I have a simple question for a topic that schould be simple and I want a simple answer and not a Tips and trics guide, that is not even considered fitting for this Q&A Format.

And I got that simple answer Thanks verry much !

Are you looking for [Type.IsAssignableFrom](https://msdn.microsoft.com/library/system.type.isassignablefrom.aspx)? — Corak, Apr 27 '18 at 11:11
Haven't you checked- https://stackoverflow.com/questions/5482844/how-to-compare-types ? — Souvik Ghosh, Apr 27 '18 at 11:12
Possible duplicate of [Hidden Features of C#?](https://stackoverflow.com/questions/9033/hidden-features-of-c) — user234461, Apr 27 '18 at 11:13
So where is the question? You have already provided an example, what is missing here? — Alpay, Apr 27 '18 at 11:19

score 2 · Answer 1 · answered Apr 27 '18 at 11:47

2

T.UnderlyingSystemType == typeof(A)

is another way to compare types

answered Apr 27 '18 at 11:47

MuKa

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2
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score 1 · Accepted Answer · answered Apr 27 '18 at 11:26

1

This can be done by taking the object's type and comparing it against a string value. You do not need the Type member.

using System;

namespace ConsoleApplication1
{
    class Program
    {
        public static Type T; //Not needed

        public class TypeA
        {
            public int testProp { get; set; }

            public string testPropTwo { get; set; }
        }

        public class TypeB
        {
            public decimal testProp { get; set; }

            public bool testPropTwo { get; set; }
        }

        static void Main(string[] args)
        {
            TypeA typeA = new TypeA();
            TypeB typeB = new TypeB();

            //Read type of user input. Mimicking dynamic value
            var inputType = Console.ReadLine();

            //Comparison with types.
            Console.WriteLine(typeA.GetType().Name == inputType);

            Console.WriteLine(typeB.GetType().Name == inputType);

            Console.ReadKey();
        }
    }
}

answered Apr 27 '18 at 11:26

well but how does *that* answer the question now? it neither addresses the intricacies of the `is` operator vs. the `typeof(t)==T` approach, nor does it replicate the almost-MVCE of OP – Cee McSharpface Apr 27 '18 at 11:28
1

Here is the point of the initial question - "please give an example on how to make a working type comparison with a changeable type". Hence the answer. – Apr 27 '18 at 11:29
ok, fair point; still the use of string representations of type names adds yet another layer to the puzzle IMO – Cee McSharpface Apr 27 '18 at 11:30
1

What I saw was a fairly standard requirement. Often in projects we have to compare types at runtime, hence I presumed (maybe wrongly) that it is a straightforward concern. – Apr 27 '18 at 11:32
It answered the question percisely thanks verry much! – majorTom Apr 27 '18 at 11:35
Glad that is the case. Cheers! – Apr 27 '18 at 11:37

score 0 · Answer 3 · answered Apr 27 '18 at 12:38

In Essence what i was loking for is something like this :

    public static bool isObjOfType(Object OBJ, Type Type)
    {
        return OBJ.GetType().Name == Type.Name;
    }

    public static bool isObjOfType(Object OBJ, string Type)
    {
        return OBJ.GetType().Name == Type;
    }

c# "is" comparison with type stored in variable --

3 Answers3