Function application to convert variables into arrays in php

//Given variables
$city = "Heze";
$province = "Shandong Province";
$project = "PHP Program";
$location_vars = array("province" , "city");
//Create an array
$result = compact("project", "nothing", "location_vars");
print_r($result);
?>

at In the above program, because there is no variable named "nothing", the output of the program is as follows: Array ( [project] => PHP Program [province] => Shandong Province [city] => Heze )