String with array structure to Array [duplicate]

Question

I have string:

Main.Sub.SubOfSub

And some kind of data, may be a string:

SuperData

How I can transform it all to this array above?

Array
(
[Main] => Array
    (
        [Sub] => Array
            (
                [SubOfSub] => SuperData
            )

    )

)

Thanks for help, PK

Answer 1

Given the values

$key = "Main.Sub.SubOfSub";
$target = array();
$value = "SuperData";

Here's some code I have lying around that does what you need¹:

$path = explode('.', $key);
$root = &$target;

while(count($path) > 1) {
    $branch = array_shift($path);
    if (!isset($root[$branch])) {
        $root[$branch] = array();
    }

    $root = &$root[$branch];
}

$root[$path[0]] = $value;

See it in action.

¹ Actually it does slightly more than that: it can be trivially encapsulated inside a function, and it is configurable on all three input values (you can pass in an array with existing values, and it will expand it as necessary).

Answer 2

Like Jon suggested (and being asking feedback for in chat), a reference/variable alias is helpful here to traverse the dynamic stack of keys. So the only thing needed is to iterate over all subkeys and finally set the value:

$rv = &$target;
foreach(explode('.', $key) as $pk)
{
    $rv = &$rv[$pk];
}
$rv = $value;
unset($rv);

The reference makes it possible to use a stack instead of recursion which is generally more lean. Additionally this code prevents to overwrite existing elements in the $target array. Full example:

$key = "Main.Sub.SubOfSub";
$target = array('Main' => array('Sub2' => 'Test'));
$value = "SuperData";

$rv = &$target;
foreach(explode('.', $key) as $pk)
{
    $rv = &$rv[$pk];
}
$rv = $value;
unset($rv);

var_dump($target);

Output:

array(1) {
  ["Main"]=>
  array(2) {
    ["Sub2"]=>
    string(4) "Test"
    ["Sub"]=>
    array(1) {
      ["SubOfSub"]=>
      string(9) "SuperData"
    }
  }
}

Demo

Related Question(s):

• dynamic array key additions
• How to group elements of array?