Pass in Type to check against

Question

Hi everyone,

I have a method in which I'm doing a check to see if the current object in a loop is the same type as a type I pass into the method.

At first I was passing the type into the method as a string and then using:

item.GetType().ToString().Equals(myType);

What I'd really prefer to do is use the is keyword to do:

item is myType

The problem I'm having is passing in myType to the method. Do I need to use some kind of funky generics type or something? What type do I pass in a reference ot a type as?

Answer 1

You can use the normal equality operator:

item.GetType() == myType;

This will return true if item is of the exact type that myType describes. Note that it will return false if there is any difference, though:

class A { }
class B : A { }

B item = new B();
Type myType = typeof(A);
bool sameType = item.GetType() == myType; // this will be false

One good thing to know about Type objects is this text that is to be found in the documentation:

A Type object that represents a type is unique; that is, two Type object references refer to the same object if and only if they represent the same type. This allows for comparison of Type objects using reference equality.

Answer 2

Do you mean something like:

    public List<T> GetItemsOfType<T>(List<object> allObjects)
    {
        return allObjects.Where(o => o is T).Cast<T>().ToList();
    }

Which you would then call with something like

var result = GetItemsOfType<MyType>(myObjects);

Answer 3

Is it something like this?

public static bool ContainsType<T>()
{
    object[] objects = new object[] { };

    foreach (var o in objects)
    {
        if (o is T)
        {
            return true;
        }
    }

    return false;
}

public static void Main(string[] args)
{
    ContainsType<int>();
}