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PHP: array_key_exists - Manual

array_key_exists

(PHP 4 >= 4.0.7, PHP 5, PHP 7, PHP 8)

array_key_exists — Checks if the given key or index exists in the array

Parameters

key: Value to check.
array: An array with keys to check.

Return Values

Returns true on success or false on failure.

Note:

array_key_exists() will search for the keys in the first dimension only. Nested keys in multidimensional arrays will not be found.

Examples

Example #1 array_key_exists() example

<?php $searchArray = ['first' => 1, 'second' => 4]; var_dump(array_key_exists('first', $searchArray)); ?>

The above example will output:

Example #2 array_key_exists() vs isset()

isset() does not return true for array keys that correspond to a null value, while array_key_exists() does.

<?php

    $searchArray = ['first' => null, 'second' => 4];var_dump(isset($searchArray['first']));
var_dump(array_key_exists('first', $searchArray));
?>

The above example will output:

See Also

isset() - Determine if a variable is declared and is different than null
array_keys() - Return all the keys or a subset of the keys of an array
in_array() - Checks if a value exists in an array
property_exists() - Checks if the object or class has a property

Rumour ¶

2 years ago

In PHP7+ to find if a value is set in a multidimensional array with a fixed number of dimensions, simply use the Null Coalescing Operator: ?? 
  So for a three dimensional array where you are not sure about any of the keys actually existing
  <?php$exists = array_key_exists($key1, $arr) && array_key_exists($key2, $arr[$key1]) && array_key_exists($key3, $arr[$key1][$key2]) ;$exists = array_key_exists($key3, $arr[$key1][$key2]??[]) ;?>

Julian ¶

2 years ago

When you want to check multiple array keys: 
  <?php 
  $array= [];
$array['a'] = '';
$array['b'] = '';
$array['c'] = '';
$array['d'] = '';
$array['e'] = '';var_dump(array_keys_exists(['a','b','c'], $array)); function array_keys_exists(array $keys, array $array): bool
{
$diff = array_diff_key(array_flip($keys), $array);

   return count($diff) === 0;

   }

developerxyz852 at gmail dot com ¶

4 months ago

<?php$userProfile = [
'name' => 'John Doe',
'email' => 'john.doe@example.com',
'age' => 30,
'country' => 'USA'
];$keyToCheck = 'email';if (array_key_exists($keyToCheck, $userProfile)) {

    echo "The key '$keyToCheck' exists in the array with value: " . $userProfile[$keyToCheck];

    } else {

    echo "The key '$keyToCheck' does not exist in the array.";

    }?>

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