Yet another simpler, faster is_assoc():
<?php
function is_assoc($array) {
foreach (array_keys($array) as $k => $v) {
if ($k !== $v)
return true;
}
return false;
}
?>
In my tests it runs about twice as fast as Michael/Gabriel's array_reduce() method.
(Speaking of which: Gabriel's version doesn't work as written; it reports associative arrays as numeric if only the first key is non-numeric, or if the keys are numeric but ordered backwards. Michael solves this problem by comparing array_reduce() to count(), but that costs another function call; it also works to just compare to -1 instead of 0, and therefore return -1 as the ternary else from the callback).
