c# - Exception when trying to convert TextBox content -

it possible write following condition?

if (textbox.text != null) 

because when have written condition in program, it throws exception.

if data type of textbox string nullable ?

the reason particular line of code should cause error if textbox variable null. exact exception?

also handy tip: if want check empty text box recommend string.isnullorwhitespace(textbox.text) return bool. it's great if statements this.