php null value confusion in switch statement

Question

I have the following php code that gives me an unexpected result:

$foo = NULL;  switch($foo) {     case 0:         print "What?!"; } 

I'd expect the result to be nothing, but it matches case 0. The php manual says that NULL is a non-value, so how can it equal 0?

Answer 1

The switch statement applies loose comparison which means that the following things are treated as equivalent to 0:

false 0 "0" NULL "any string" ""