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

Question

This works just fine:

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

    }

Is ther

Answer 1

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)) { //... }

Answer 2

Couldn't you also do the more verbose "old" way, before the is keyword:

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

Answer 3

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

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

instead of

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

Answer 4

Try this.

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

Answer 5

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) {...}

Answer 6

This is one way:

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