Check if a “run-time” multidimensional array key exists

Question

I have a multidimensional array. I need a function that checks if a specified key exists.

Let\'s take this array

$config[\'lib\'][\'template\'][\'eng         


        

Answer 1

I created the following two functions to do solve the same problem you are having.

The first function check is able to check for one/many keys at once in an array using a dot notation. The get_value function allows you to get the value from an array or return another default value if the given key doesn't exist. There are samples at the bottom for basic usage. The code is mostly based on CakePHP's Set::check() function.

<?php

function check($array, $paths = null) {
    if (!is_array($paths)) {
        $paths = func_get_args();
        array_shift($paths);
    }

    foreach ($paths as $path) {
        $data = $array;

        if (!is_array($path)) {
            $path = explode('.', $path);
        }

        foreach ($path as $i => $key) {
            if (is_numeric($key) && intval($key) > 0 || $key === '0') {
                $key = intval($key);
            }

            if ($i === count($path) - 1 && !(is_array($data) && array_key_exists($key, $data))) {
                return false;
            }

            if (!is_array($data) || !array_key_exists($key, $data)) {
                return false;
            }

            $data =& $data[$key];
        }       
    }

    return true;
}

function get_value($array, $path, $defaultValue = FALSE) {    
    if (!is_array($path))
        $path = explode('.', $path);

    foreach ($path as $i => $key) {
        if (is_numeric($key) && intval($key) > 0 || $key === '0')
            $key = intval($key);

        if ($i === count($path) - 1) {
            if (is_array($array) && array_key_exists($key, $array))
                return $array[$key];
            else
                break;
        }

        if (!is_array($array) || !array_key_exists($key, $array))
            break;

        $array = & $array[$key];
    }

    return $defaultValue;
}

// Sample usage
$data = array('aaa' => array(
            'bbb' => 'bbb',
            'ccc' => array(
                'ffffd' => 'ffffd'
            )
        ));

var_dump( check($data, 'aaa.bbb') ); // true
var_dump( check($data, 'aaa.bbb', 'aaa.ccc') ); // true
var_dump( check($data, 'zzz') ); // false
var_dump( check($data, 'aaa.bbb', 'zzz') ); // false

var_dump( get_value($data, 'aaa.bbb', 'default value') ); // "bbb"
var_dump( get_value($data, 'zzz', 'default value') ); // "default value"

Answer 2

function checkKey($array) {
  $args = func_get_args();
  for ($i = 1; $i < count($args); $i++) {
    if (!isset($array[$args[$i]]))
       return false;
    $array = &$array[$args[$i]];
  }
  return true;
}

Usage:

checkKey($config, 'lib', 'template', 'engine');
checkKey($config, 'genericSetting');