Check if specific array key exists in multidimensional array - PHP

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慢半拍i
慢半拍i 2020-11-27 18:53

I have a multidimensional array e.g. (this can be many levels deep):

$array = Array ( 
    [21] => Array ( ) 
    [24] => Array ( 
        [22] => A         


        
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6条回答
  • 2020-11-27 19:28

    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

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  • 2020-11-27 19:28
    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>';
    }
    
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  • 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;
    }
    
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  • 2020-11-27 19:48

    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;
    }
    
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  • 2020-11-27 19:51

    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;
              }
           }
        }
    }
    
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  • 2020-11-27 19:53

    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":'

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