asp.net server control reference

Question

Hi,

 I am familiar with this piece of code:

LinkButton myLb = (LinkButton)sender;
string cmd2 = myLb.CommandName;

 

However I came across this new code to me , but it does the same thing as the upper code. 

                string cmd = (sender as LinkButton).CommandName;

my question, is this a way of casting. How do I know when to use this kind of conversion.

 

Thanks

 

Al