Today I learned about a special case of array_map()
in PHP, which is mentioned as a side note in the documentation:
Example #4 Creating an array of arrays
<?php $a = array(1, 2, 3, 4, 5); $b = array("one", "two", "three", "four", "five"); $c = array("uno", "dos", "tres", "cuatro", "cinco"); $d = array_map(null, $a, $b, $c); print_r($d); ?>
The above example will output:
Array ( [0] => Array ( [0] => 1 [1] => one [2] => uno ) [1] => Array ( [0] => 2 [1] => two [2] => dos ) [2] => Array ( [0] => 3 [1] => three [2] => tres ) [3] => Array ( [0] => 4 [1] => four [2] => cuatro ) [4] => Array ( [0] => 5 [1] => five [2] => cinco ) )
If the array argument contains string keys then the returned array will contain string keys if and only if exactly one array is passed. If more than one argument is passed then the returned array always has integer keys.
But that's it. No more explanation. I understand, that this does the same as
$d = array_map(function() { return func_get_args(); }, $a, $b, $c);
But why would anybody want or expect this as default behavior? Is there a technical reason why it works like that, like a side effect from the implemtation? Or was this just a random "let's make this function do one more thing" decision (looking at you, array_multisort()
)?