Check if object is NOT of type (!= equivalent for “IS”) – C#

This works just fine:

    protected void txtTest_Load(object sender, EventArgs e)
    {
        if (sender is TextBox) {...}

    }

Is there a way to check if sender is NOT a TextBox, some kind of an equivalent of != for “is”?

Please, don’t suggest moving the logic to ELSE{} 🙂

Answers:

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Method 1

This is one way:

if (!(sender is TextBox)) {...}

Method 2

C# 9 allows using the not operator. You can just use

if (sender is not TextBox) {...}

instead of

if (!(sender is TextBox)) {...}

Method 3

Couldn’t you also do the more verbose “old” way, before the is keyword:

if (sender.GetType() != typeof(TextBox)) { // ... }

Method 4

Two well-known ways of doing it are :

1) Using IS operator:

if (!(sender is TextBox)) {...}

2) Using AS operator (useful if you also need to work with the textBox instance) :

var textBox = sender as TextBox;  
if (sender == null) {...}

Method 5

If you use inheritance like:

public class BaseClass
{}
public class Foo : BaseClass
{}
public class Bar : BaseClass
{}

…
Null resistant

if (obj?.GetType().BaseType != typeof(Bar)) { // ... }

or

if (!(sender is Foo)) { //... }

Method 6

Try this.

var cont= textboxobject as Control;
if(cont.GetType().Name=="TextBox")
{
   MessageBox.show("textboxobject is a textbox");
}

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