Php "" and 0 return same value

Php "" and 0 return same value

$page_now=array_search($id, $user_id);
if($page_now==""){return TURE;}
else{return FALSE}//include [0]index
I have an array_search, if it can't find the match it will return "",
However I have problem on [0] index
if the search index return 0 which is 1st one from array.
if statement $page_now=="" & $page_now==0 both are return TURE
Try this
$var=0;
if($var!=""){echo "have value in var";}else{echo "no value in var";}
I want it return have value even it is 0