If I have the following array:

[
  'foo',
  'bar',
  'baz' 
]

How can I get this output with PHP dynamically:

[
  'foo' => [
    'bar' => [
      'baz' => []
    ]
  ]
]

EDIT

I ended up achieving it by building the array backward and keeping track of the last key, but I would be interested in a cleaner recursive approach:

$arr = ['foo', 'bar', 'baz'];
$new_arr = [];
$last_key = null;

foreach ( array_reverse( $arr ) as $item ) {
    if ( $last_key ) {
        $new_arr[ $item ] = $new_arr;
        unset( $new_arr[ $last_key ] );
        $last_key = $item;
    } else {
        $new_arr[ $item ] = [];
        $last_key = $item; 
    }
}

CodePudding user response：

$arr = [ 'foo', 'bar', 'baz' ];

$new_arr = array_reduce(array_reverse($arr), static fn($carry, $item) => [ $item => $carry ], []);

Steps:

1. Reverse the array.
2. Reduce the reversed array. On each iteration return [ $item => $carry ].

CodePudding user response：

Try this:

function buildNestedArray($arr) {
  if (!$arr) {
    return [];
  }
  return [ $arr[0] => buildNestedArray(array_slice($arr, 1))];
}