Check if object is NOT of type (!= equivalent for

问题:

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{} :)

回答1:

This is one way:

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

回答2:

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

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

回答3:

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) {...}

回答4:

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)) { //... }

回答5:

Try this.

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