How to sort a multidimensional array on PHP where keys are not string labels

Question

I have this multidimensional array:

$serviceTimes = Array (
  [0] => Array ( [0] => PM1900 [1] => 7:00pm )
  [1] => Array ( [0] => PM1900 [1] => 7:00pm )
  [2] => Array ( [0] => PM1415 [1] => 2:15pm )
  [3] => Array ( [0] => PM1919 [1] => 7:19pm )
  [6] => Array ( [0] => PM2020 [1] => 8:20pm )
)

But I am unable to sort the array on the [0] element. This does not work:

array_multisort( $serviceTimes[0], SORT_ASC, $serviceTimes );

nor does this work

array_multisort( $serviceTimes[][0], SORT_ASC, $serviceTimes );

Any thoughts?

Ideally and ultimately, this is what I am looking to produce:

Array (
  [0] => 2:15pm )
  [1] => 7:00pm )
  [2] => 7:00pm )
  [3] => 7:19pm )
  [4] => 8:20pm )
)

Answer 1

Use array_column to extract the 0 column from the sub-arrays and sort on that:

array_multisort(array_column($serviceTimes, 0), SORT_ASC, $serviceTimes);

You state sorting on the 0 element but your output shows times from the 1 element. If so just change the array_column argument to a 1.