$my_arr1 = array();

$my_arr1[] = "Hello";
$my_arr1[] = "Home";
$my_arr1[] = "Good";

$index = array_search("Home", $my_arr1);
if ($index == false)
     echo "not found";
else
     echo $index;
// на экране увидим 1

$index = array_search("Car", $my_arr1);
if ($index == false)
     echo "not found";
else
     echo $index;
// на экране увидим not found