PHP Taskbook Level 8.1

Given some URL:

php$url = 'http://test.com/dir1/dir2/dir3/page.html';

Get the domain name from it:

php'test.com';

Given an array:

php[
  [1, 2, 3],
  [1, 2],
  [1, 2, 3, 4, 5],
  [1],
  [1, 2, 3, 4],
]

Sort the array elements in ascending order of the number of elements in the subarray.

Given an array:

php[
  [2, 4, 5],
  [1, 2, 3],
  [0, 1, 1],
  [5, 7, 1],
]

Sort the array elements in ascending order of the sum of the subarray elements.

Display the following pyramid on the screen: