Sorting array ignoring special characters in PHP

Question

I have an array:

Array (
       '9:00',
       '22:00',
       '12:00',
       '*15:00'
)

I'm trying to sort as this way:

Array (
       '9:00',
       '12:00',
       '*15:00',
       '22:00'
)

Is that possible? I'm trying to ignore the asterisk in the array to sort, but the asterisk remains in the element.

Is the asterisk in front of the 15 a typo? Or is it meant to be there? Are there any other of such characters in the data set? — lxg
– lxg, Commented Sep 18, 2014 at 18:37
If you want to keep asterisk, then you probably need to write your own sorting function. So far, there is no built in function to do that. — RNK
– RNK, Commented Sep 18, 2014 at 18:38
There is no way to sort natively in PHP if you have something like a * preceding. You'll need to make a function to strip leading special chars, use natcasesort (probably the best here) and then reference keys to the original array to get the real value. — Kohjah Breese
– Kohjah Breese, Commented Sep 18, 2014 at 18:38

lxg · Accepted Answer · 2014-09-18 18:43:08Z

2

How about this:

$foo = array('9:00', '22:00', '12:00', '*15:00');

usort($foo, function($a, $b) {
    $a = preg_replace('|[^\d:]|', '', $a);
    $b = preg_replace('|[^\d:]|', '', $b);

    return strnatcmp($a, $b);
});

print_r($foo);

Output:

Array
(
    [0] => 9:00
    [1] => 12:00
    [2] => *15:00
    [3] => 22:00
)

answered Sep 18, 2014 at 18:43

lxg

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Comments

mickmackusa · Accepted Answer · 2022-08-04 22:16:06Z

Logically, your strings will have between 4 and 6 characters. By left padding every string with asterisks to a standard length of 6 characters, you no longer need to perform a natural sort to accommodate missing zeros or asterisks.

Using array_multisort() will offer better performance because the data-mutating step will make n iterated calls of sprintf(), but usort() will call preg_replace() twice and strnatcmp() once n log n times (IOW, it's more expensive).

'*6 means left pad the string (%s) with the * character to ensure that the string has a length of 6 characters.

Code: (Demo)

$array = [
       '12:00',
       '*15:00',
       '9:00',
       '22:00'
];

array_multisort(
    array_map(fn($v) => sprintf("%'*6s", $v), $array),
    $array
);
var_export($array);

Output:

array (
  0 => '9:00',
  1 => '12:00',
  2 => '*15:00',
  3 => '22:00',
)

Of course this will work just the same too if you don't want to make mapped calls of anything: (Demo)

array_multisort(
    str_replace('*', '', $array),
    SORT_NATURAL,
    $array
);
var_export($array);

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