CODEWITHSUNDEEP
phparraysrecursion
Haddad
Haddad

Reputation: 379

Getting a value of an array index using variable variable

I have a recursive array depth of which is variable, and I want to be able to take a string with a separator and convert that string to an index in that array,

For example

$path = 'level1.level2.level3';

will be converted to get the value 'my data' from the array below

$data['level1']['level2']['level3'] = 'my data';

I thought the quickest way to get this would be to use variable variables, but when I try the following code

$index = "data['level1']['level2']['level3']";

echo $$index;

I get the follwing error

PHP Notice:  Undefined variable: data['level1']['level2']['level3']

All other ways I can think of doing this are very inefficient, could someone please shed some light on this, is it possible using variable variables for arrays in PHP? Any other efficient workaround?

Many thanks.

Upvotes: 0

Views: 158

Answers (5)

DaveRandom
DaveRandom

Reputation: 88697

It is a tricky one this, here is the most efficient way I can think of:

function get_value_from_array ($array, $path, $pathSep = '.') {
  foreach (explode($pathSep, $path) as $pathPart) { 
    if (isset($array[$pathPart])) {
      $array = $array[$pathPart];
    } else { 
      return FALSE;
    }
  }
  return $array;
}

Returns the value, or FALSE on failure.

Upvotes: 2

Aleks G
Aleks G

Reputation: 57326

You can use eval function like so:

$data['level1']['level2']['level3'] = 'my data';
eval("\$index = \$data['level1']['level2']['level3'];");
echo $index;

Upvotes: -1

awm
awm

Reputation: 6570

Something like this:

eval('$data[\''.implode("']['",explode('.',$path))."'] = 'my data';");

...but don't ever, ever tell anyone I told you to do this.

Upvotes: -1

Berry Langerak
Berry Langerak

Reputation: 18859

You'll have to loop the array, you won't manage to do this using variable variables, as far as I know. This seems to work though:

<?php

function retrieve( $array, $path ) {
    $current = $array;
    foreach( explode( '.', $path ) as $segment ) {
        if( false === array_key_exists( $segment, $current ) ) {
            return false;
        }
        $current = $current[$segment];
    }
    return $current;
}

$path = 'level1.level2.level3';

// will be converted to get the value 'my data' from the array below
$data['level1']['level2']['level3'] = 'my data';

var_dump( retrieve( $data, $path ) );

Upvotes: 2

genesis
genesis

Reputation: 50974

Try

$index = "data";
echo $$index['level1']['level2']['level3'];

instead, because $index should be only variable name

Upvotes: 0

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