按日期排序PHP排序数组（Chatlog）（保持等效日期的顺序）

Question

I have a chatlog composed of a date and the actual entry after two spaces. Now I need to sort this by the time of the entry, but keep the order of the entries the same when the dates are equivalent.

Array
(
    [0] => '6/4 17:01:30.001  X'
    [1] => '6/4 17:01:30.003  B'
    [2] => '6/4 17:01:30.003  C'
    [3] => '6/4 17:01:30.003  A'
    [4] => '6/4 17:01:30.002  Y'
)

I already tried a couple of things, creating a multidimensional array splitted in the dates an values sorting with a couple of different algorithms but I'm pretty sure there must be some really easy, and obvious way to do this without multiple loops.

The result should look like this:

Array
(
    [0] => '6/4 17:01:30.001  X'
    [4] => '6/4 17:01:30.002  Y'
    [1] => '6/4 17:01:30.003  B'
    [2] => '6/4 17:01:30.003  C'
    [3] => '6/4 17:01:30.003  A'
)

Answer 1

We can take advantage of the fact that your date string will sort in the correct order. Just use that as a key and do a ksort:

// Starting array
$aArray = array(
    '6/4 17:01:30.001  X',
    '6/4 17:01:30.002  Y',
    '6/4 17:01:30.003  B',
    '6/4 17:01:30.003  C',
    '6/4 17:01:30.003  A'
);

// Parse out the date and use it as a key. There might be a better regex to use here, but this works...
$aKeyed = array();
foreach($aArray as $value)
{
    preg_match('/([0-9]*\/[0-9]* [0-9]*:[0-9]*:[0-9]*\.[0-9]*)  (.*)/', $value, $aMatches);
    $aKeyed[$aMatches[1]][] = $aMatches[0];
}

// Sort by key.
ksort($aKeyed);

// Iterate the keyed array to get values into the output array. Order is preserved since we appended things to the value of the keyed array in the correct order.
$aOut = array();
foreach($aKeyed as $aValue)
{
    foreach($aValue as $value)
    {
        // Although there are t2 loops, the total number of iterations is the same as the single loop above.
        $aOut[] = $value;
    }
}

// Print results.
var_export($aOut);

Output:

array (
  0 => '6/4 17:01:30.001  X',
  1 => '6/4 17:01:30.002  Y',
  2 => '6/4 17:01:30.003  B',
  3 => '6/4 17:01:30.003  C',
  4 => '6/4 17:01:30.003  A',
)