- var_dump: documentation ( source)
- array_search: documentation ( source)
<?php
$arr = array();
$arr["a"] = "A";
$arr["b"] = "B";
/*$str = array_filter($arr, function($e1){
echo $e1;
return $e1;
});*/
$str = array_search("B", $arr);
var_dump($str);