Check if specific array key exists in multidimensional array - PHP - php

Question

I have a multidimensional array e.g. (this can be many levels deep):
$array = Array (
[21] => Array ( )
[24] => Array (
[22] => Array ( )
[25] => Array (
[26] => Array ( )
)
)
)
I am trying to loop through it to see if a certain key exists:
$keySearch = 22; // key searching for
function findKey($array, $keySearch) {
foreach ($array as $item){
if (isset($item[$keySearch]) && false === findKey($item[$keySearch], $item)){
echo 'yes, it exists';
}
}
}
findKey($array, $keySearch);
But it finds nothing. Is there an error in the loop?

Answer 1

array_key_exists() is helpful.
Then something like this:
function multiKeyExists(array $arr, $key) {
// is in base array?
if (array_key_exists($key, $arr)) {
return true;
}
// check arrays contained in this array
foreach ($arr as $element) {
if (is_array($element)) {
if (multiKeyExists($element, $key)) {
return true;
}
}
}
return false;
}
Working example: http://codepad.org/GU0qG5su

Answer 2

I played with your code to get it working :
function findKey($array, $keySearch)
{
foreach ($array as $key => $item) {
if ($key == $keySearch) {
echo 'yes, it exists';
return true;
} elseif (is_array($item) && findKey($item, $keySearch)) {
return true;
}
}
return false;
}

Answer 3

Here is a one line solution:
echo strpos(json_encode($array), $key) > 0 ? "found" : "not found";
This converts the array to a string containing the JSON equivalent, then it uses that string as the haystack argument of the strpos() function and it uses $key as the needle argument ($key is the value to find in the JSON string).
It can be helpful to do this to see the converted string: echo json_encode($array);
Be sure to enclose the needle argument in single quotes then double quotes because the name portion of the name/value pair in the JSON string will appear with double quotes around it. For instance, if looking for 22 in the array below then $key = '"22"' will give the correct result of not found in this array:
$array =
Array (
21 => Array ( ),
24 =>
Array (
522 => Array ( ),
25 =>
Array (
26 => Array ( )
)
)
);
However, if the single quotes are left off, as in $key = "22" then an incorrect result of found will result for the array above.
EDIT: A further improvement would be to search for $key = '"22":'; just incase a value of "22" exists in the array. ie. 27 => "22" In addition, this approach is not bullet proof. An incorrect found could result if any of the array's values contain the string '"22":'

Answer 4

function findKey($array, $keySearch)
{
// check if it's even an array
if (!is_array($array)) return false;
// key exists
if (array_key_exists($keySearch, $array)) return true;
// key isn't in this array, go deeper
foreach($array as $key => $val)
{
// return true if it's found
if (findKey($val, $keySearch)) return true;
}
return false;
}
// test
$array = Array (
21 => Array ( 24 => 'ok' ),
24 => Array (
22 => Array ( 29 => 'ok' ),
25 => Array (
26 => Array ( 32 => 'ok' )
)
)
);
$findKeys = Array(21, 22, 23, 24, 25, 26, 27, 28, 29, 30);
foreach ($findKeys as $key)
{
echo (findKey($array, $key)) ? 'found ' : 'not found ';
echo $key.'<br>';
}

Answer 5

returns false if doesn't exists, returns the first instance if does;
function searchArray( array $array, $search )
{
while( $array ) {
if( isset( $array[ $search ] ) ) return $array[ $search ];
$segment = array_shift( $array );
if( is_array( $segment ) ) {
if( $return = searchArray( $segment, $search ) ) return $return;
}
}
}
return false;
}

Answer 6

For sure some errors, is this roughly what you are after? (Untested code):
$keySearch=22; // key seraching for
function findKey($array, $keySearch)
{
// check whether input is an array
if(is_array($array)
{
foreach ($array as $item)
{
if (isset($item[$keySearch]) || findKey($item, $keysearch) === true)
{
echo 'yes, it exists';
return true;
}
}
}
}

Answer 7

Here is one solution that finds and return the value of the key in any dimension array..
function findValByKey($arr , $keySearch){
$out = null;
if (is_array($arr)){
if (array_key_exists($keySearch, $arr)){
$out = $arr[$keySearch];
}else{
foreach ($arr as $key => $value){
if ($out = self::findValByKey($value, $keySearch)){
break;
}
}
}
}
return $out;
}

Answer 8

I did modified to return value of searched key:
function findKeyInArray($array, $keySearch, &$value)
{
foreach ($array as $key => $item) {
if ($key === $keySearch) {
$value = $item;
break;
} elseif (is_array($item)) {
findKeyInArray($item, $keySearch,$value);
}
}
}
$timeZone = null;
findKeyInArray($request, 'timezone', $timeZone);