PHP array to tree array

Question

I have a problem I cannot fix. I have 2 arrays and a string. The first array contains the keys the second one should use. The first one is like this:

Array
(
    [0] => foo
    [1] => bar
    [2] => hello
)

Now I need a PHP code that converts it to the second array:

Array
(
    [foo] => Array
        (
            [bar] => Array
                (
                    [hello] => MyString
                )
        )
)

The number of items is variable.

Can someone please tell me how to do this?

What have you tried?

Niet the Dark Absol
– Niet the Dark Absol

2013-03-30 14:08:19 +00:00
Commented Mar 30, 2013 at 14:08 — Niet the Dark Absol
– Niet the Dark Absol, Commented Mar 30, 2013 at 14:08
Walk the array back to front ;-)

Havelock
– Havelock

2013-03-30 14:10:34 +00:00
Commented Mar 30, 2013 at 14:10 — Havelock
– Havelock, Commented Mar 30, 2013 at 14:10

Mikhail Chernykh · Accepted Answer · 2013-03-30 14:38:42Z

3

You should use references to solve this problem:

$a = array (0 => 'foo', 1 => 'bar', 2 => 'hello' );

$b = array();
$ptr = &$b;
foreach ($a as $val) {
    $ptr[$val] = Array();
    $ptr = &$ptr[$val];
}
$ptr = 'MyString';
var_dump($b);

edited Mar 30, 2013 at 14:38

answered Mar 30, 2013 at 14:11

Mikhail Chernykh

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1 Comment

Wietse de Vries Over a year ago

Thanks! The problem was that I didn't know the use of &.

Baba · Accepted Answer · 2013-03-30 14:11:41Z

2

All you need is :

$path = array(
        0 => 'foo',
        1 => 'bar',
        2 => 'hello'
);

$data = array();
$t = &$data;
foreach ( $path as $key ) {
    $t = &$t[$key];
}
$t = "MyString";
unset($t);

print_r($data);

See Live Demo

answered Mar 30, 2013 at 14:11

Baba

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1 Comment

Wietse de Vries Over a year ago

Thanks, but Netme was a bit faster.

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