How to recursively create a multidimensional array?

Question

I am trying to create a multi-dimensional array whose parts are determined by a string. I'm using . as the delimiter, and each part (except for the last) should be an array
ex:

config.debug.router.strictMode = true

I want the same results as if I were to type:

$arr = array('config' => array('debug' => array('router' => array('strictMode' => true))));

This problem's really got me going in circles, any help is appreciated. Thanks!

Answer 1

I say split everything up, start with the value, and work backwards from there, each time through, wrapping what you have inside another array. Like so:

$s = 'config.debug.router.strictMode = true';
list($parts, $value) = explode(' = ', $s);

$parts = explode('.', $parts);
while($parts) {
   $value = array(array_pop($parts) => $value);
}

print_r($parts);

Definitely rewrite it so it has error checking.

Answer 2

Let’s assume we already have the key and value in $key and $val, then you could do this:

$key = 'config.debug.router.strictMode';
$val = true;
$path = explode('.', $key);

Builing the array from left to right:

$arr = array();
$tmp = &$arr;
foreach ($path as $segment) {
    $tmp[$segment] = array();
    $tmp = &$tmp[$segment];
}
$tmp = $val;

And from right to left:

$arr = array();
$tmp = $val;
while ($segment = array_pop($path)) {
    $tmp = array($segment => $tmp);
}
$arr = $tmp;

Answer 3

// The attribute to the right of the equals sign
$rightOfEquals = true; 

$leftOfEquals = "config.debug.router.strictMode";

// Array of identifiers
$identifiers = explode(".", $leftOfEquals);

// How many 'identifiers' we have
$numIdentifiers = count($identifiers);


// Iterate through each identifier backwards
// We do this backwards because we want the "innermost" array element
// to be defined first.
for ($i = ($numIdentifiers - 1); $i  >=0; $i--)
{

   // If we are looking at the "last" identifier, then we know what its
   // value is. It is the thing directly to the right of the equals sign.
   if ($i == ($numIdentifiers - 1)) 
   {   
      $a = array($identifiers[$i] => $rightOfEquals);
   }   
   // Otherwise, we recursively append our new attribute to the beginning of the array.
   else
   {   
      $a = array($identifiers[$i] => $a);
   }   

}

print_r($a);

Answer 4

Gumbo's answer looks good.

However, it looks like you want to parse a typical .ini file.

Consider using library code instead of rolling your own.

For instance, Zend_Config handles this kind of thing nicely.