unset only removes the value, and I want to remove the keys as well.
What to use for this?

Answer 1, authority 100%

1)

$ new_array = array_filter ($ old_array, function ($ element) {
  return! empty ($ element);
});

2)

$ new_array = array_diff ($ old_array, array (''));

Answer 2, authority 17%

I went to look at the solution to a rather pressing problem. With a cursory glance, I looked around the topic and saw that there was no normal solution yet. I wrote the following:

foreach ($ old_array as $ element) {
        if (! empty ($ element)) {
          $ new_array [] = $ element;
        }
      }

Not elegant, but very simple and, most importantly, it works 🙂

Answer 3, authority 8%

Depending on what is considered an “empty” element, you can also suggest this option:

& lt;? php
$ arr = ['', 'a', 0, 2, 'd', false, 'p', '', null, 'c', 3,0];
var_dump ($ arr);
$ new_arr = array_diff ($ arr, array ('', NULL, false));
var_dump ($ new_arr);
// result
Array
(
  [0] = & gt;
  [1] = & gt; a
  [2] = & gt; 0
  [3] = & gt; 2
  [4] = & gt; d
  [5] = & gt;
  [6] = & gt; p
  [7] = & gt;
  [8] = & gt;
  [9] = & gt; c
  [10] = & gt; 3
  [11] = & gt; 0
)
Array
(
  [1] = & gt; a
  [2] = & gt; 0
  [3] = & gt; 2
  [4] = & gt; d
  [6] = & gt; p
  [9] = & gt; c
  [10] = & gt; 3
  [11] = & gt; 0
)

Answer 4, authority 8%

I would like to note that this code is not always enough:

$ new_array = array_diff ($ old_array, array (''));

For example, this is how we can run into trouble:

$ new_array = array_diff (explode ("/", "/ level1 / level2 /"), array ('' ));

At the output we will receive

Array
(
  [1] = & gt; level1
  [2] = & gt; level2
)

Although we really wanted to get it

Array
(
  [0] = & gt; level1
  [1] = & gt; level2
)

Therefore, for such cases, we use:

$ new_array = array_values ​​(array_diff (explode ("/", "/ level1 / level2 /"), array ( '')));

Answer 5

$ file =
      array_filter ($ file,
        function ($ element)
        {
          $ element = trim ($ element);
          if (strlen ($ element))
            return true;
        }
      );

Answer 6

Try it:

unset ($ arr [0]); sort ($ arr);

And that’s it, there are no empty keys.