Check if variable null before assign to null?

Question

Is variable assignment expensive compared to a null check? For example, is it worth checking that foo is not null before assigning it null?

if (foo != null)          


        

Answer 1

If you have a decent compiler they will generate identical code. If you have a crappy compiler the one with the if will be worse. On 2009 hardware assignments to variables are very cheap, and conditional branches can sometimes be expensive.