PHP Loose comparison and null on Switch -

today saw strange bug on code. have switch comparison on case , if variable equals null or '' comes in first case.

my code :

$shost  = filter_input(input_server, 'http_host');  switch($shost){      // local     case strpos($shost, "dev.localhost") !== false: $this->_senv  = 'local';                                                     break;                  // prod     default:                                        $this->_senv = 'production';                                                     break; } 

on if statement it's work on switch case doesn't work , don't know why .. maybe php problems ? has had similar bug ?

$shost can null because run script batch.

if(strpos($shost, "dev.localhost") !== false){ // nothing } else{     return false; } 

of course can if is_null before switch , want understand why it's working that..

edit: forgot said have 5 cases on switch , 1 case environment

thank future answer :)

if $shost equals null or '', first switch case true because

var_dump($shost == (strpos($shost, "dev.localhost") !== false)); 

is true. how switch work. can this:

switch(true) {      // local     case strpos($shost, "dev.localhost") !== false:         $this->_senv  = 'local';         break;                  // prod     default:         $this->_senv = 'production';         break; }