Arrays as keys of arrays

Sometimes you need to associate an array with some kind of value, so you want to do the following:

$a = array (
  array (...) => 'good_array',
  array (...) => 'big_array',
  array (...) => 'green_array'
);

But this is not possible. While you cannot use an array as a key of another array, you still can do this:

$a = array (
  serialize (array (...)) => 'good_array',
  serialize (array (...)) => 'big_array',
  serialize (array (...)) => 'green_array'
);

That’s because serialize() returns strings, which can be a keys of an array. Now if you want to know, whether array $b is good, big or green, you can just do the following:

echo $a[serialize ($b)];

Впервые опубликовано мной на PHP.net в user contributed notes, поэтому english