Empty String in ASP.net

Question

What is difference between these three -

textbox1.text = "" 
textbox1.text = null 
textbox1.text = string.empty

Any specific case when each of them is used?

Answer 1

textbox1.text = "" and textbox1.text = string.empty both are same,will return empty string, in this case compiler will allocates memory for string with zero length.but with textbox1.text = null no space is allocated trying to acess will throw null pointer exception.