Learning PHP: Is there a way to get the value of multi-dimensional array by specifying the key with a variable?

If you have the keys as an array, then it is easy to write a function that does this: function multiArrayAccess($array, $keys) { $result = $array; foreach ($keys as $key) $result = $result[$key]; return $result; } echo multiArrayAccess($array, array('a', 'b')); or even function multiArrayAccess($array, $keys) { return array_reduce($keys, function($x, $key) { return $x[$key]; }, $array); } echo multiArrayAccess($array, array('a', 'b'));

No, there is not. This being PHP, you could do crazy things like eval('$array' . $key);, but that isn't good. However, you could let your user given an array of two keys, then use $array[$key[0]][$key[1]].

I agree with John, there's probably a better way of thinking about this that carries more abstraction and is more flexible. e.g. if you really need to store a pair of keys for one array as a separate variable, how about just make that another array: <?php $address = array( 'level1' => 'a', 'level2' => 'b' ); $result = $array[$address['level1']][$address['level2']]; echo $result;

Yes, you can directly get the array value by using a variable. foreach ($array as $key=>$val) { print_r($val); print_r($array[$key]); } In your example, here is how you could access the value of the array at index ["a"]["b"] $a = "a"; $b = "b"; print_r($array[$a][$b]);

The answer is that, yes yes yes you can do it, using recursion (sadly not much people here know algorithms and CS basics well, so I don’t think anyone here has the correct answer). Therefore, what J said is terribly wrong.You can access a specific value of a multidimentional array using specified variables as keys, when knowing its depth (which you can find using another custom-made function discussed in http://stackoverflow.com/questions/262891/is-there-a-way-to-find-out-how-deep-a-php-array-is (via Stack Overflow) The mechanism involved in finding the depth is also recursion). I had to face this problem today when trying to make a flexible web-based playground for my RESTful API, where I allow authenticated users to make custom cURL GET requests.Let’s just see the code. (This is just a crappy example I coded up in <10mins, could have bugs and can be optimized. Never use this in production without understanding it) /** * Access a specific member of an multidimensional array * given $keys as a series of keys. * @author Alexxonderros Fannggovitch * @param $array array the array to be accessed * @param $keys array a series of keys, the first one for the * top level, the second one for the second level, etc * @param $depth integer how deep the multidimensional array is */ function accessArray($array, $keys, $depth) { if($depth > 1) { return accessArray( $array[$keys[count($keys) - ($depth)]], $keys, ($depth - 1)); } else { for($i = 0; $i < count($array); $i++) { //traverse if((count($array) - 1) == $i) { return $array[$keys[$i]]; } } } } Usage example: var_dump(accessArray([ "hi" ], [0], 1)); Which will output: string(2) "hi" Note that the keys array should be a series of values for each dimension of the keys. E.g. $keys = [ "animal", "dog", "great dane", "size" ]; matched up with $array = [ "animal" => [ "dog" => [ "great dane" => [ "size" => "big" ] ] ], "alien" => "no no no", "computer" => [ "linux" ] ]; will produce the result string(3) "big" Some extended reading: https://en.wikipedia.org/wiki/Recursion (from Wikipedia).

$key = '["a"]["b"]'; echo $array{$key} will not and should not work.This will work, but I’m not clear on exactly what you’re trying to do, so this may not be the best answer either: $one = $_REQUEST["user_input_value_for_a"]; $two = $_REQUEST["user_input_value_for_b"]; print_r($array['a']["${one}"] .' '.$array['b']["{$two}"]); More than likely, John or Alexxonderros answers below are a better fit, but given the limited context here, wanted to present you with a third, simpler alternative just in case. Also note that if you do find the above to fit what you need, you’ll still need to add some form of error handling.But more to the point, although your goal here isn’t totally clear to me, I think that you are making this more complex than it needs to be. Give us more context and we can see if there’s improvements to be had.

Quite Simple: <?php // The Array $array = array( 'a' => array( 'a' => "a aaa", 'b' => "b bbb", 'c' => "c ccc", 'd' => "d ddd", ), 'b' => array( 'a' => "b aaa", 'b' => "b bbb", 'c' => "c ccc", ), ); // Lets see a specific key ( e.g. $array['b']['c']) $key_one = 'b'; $key_two = 'c'; // Spew. Expecting 'c ccc'; echo $array[$key_one][$key_two]; ?>