Call to undefined function ProjectHttpControllersarray_sort()

You can't use string and array helpers from Laravel 6. laravel 6 removed helpers function from repo. You can use IlluminateSupportArr classes for helpers.

use IlluminateSupportArr;

Arr:::sort($get_all_available_city);

If you want to use helpers functions as array_sort then you need to install new composer package with following command :

composer require laravel/helpers

Then you can access :

array_sort($get_all_available_city);

You can follow the official documentation of Laravel here

use IlluminateSupportArr;

$array = ['Desk', 'Table', 'Chair'];

$sorted = Arr::sort($array);

Laravel 7 doesn't seem to use the array_* calls anymore. Use Arr::sort() instead.

dd(Arr::sort($get_all_available_city));