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Php checking array key exists

Содержание
  1. Php checking array key exists
  2. array_key_exists
  3. Parameters
  4. Return Values
  5. Examples
  6. Notes
  7. See Also
  8. User Contributed Notes 3 notes
  9. array_key_exists
  10. Список параметров
  11. Возвращаемые значения
  12. Примеры
  13. Примечания
  14. Смотрите также
  15. key_exists
  16. User Contributed Notes

Php checking array key exists

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Источник

array_key_exists

array_key_exists() returns true if the given key is set in the array. key can be any value possible for an array index.

Parameters

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

$search_array = array( ‘first’ => 1 , ‘second’ => 4 );
if ( array_key_exists ( ‘first’ , $search_array )) echo «The ‘first’ element is in the array» ;
>
?>

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.

$search_array = array( ‘first’ => null , ‘second’ => 4 );

// returns false
isset( $search_array [ ‘first’ ]);

// returns true
array_key_exists ( ‘first’ , $search_array );
?>

Notes

Note:

For backward compatibility reasons, array_key_exists() will also return true if key is a property defined within an object given as array . This behaviour is deprecated as of PHP 7.4.0, and removed as of PHP 8.0.0.

To check whether a property exists in an object, property_exists() should be used.

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

User Contributed Notes 3 notes

When you want to check multiple array keys:

$array = [];
$array [ ‘a’ ] = » ;
$array [ ‘b’ ] = » ;
$array [ ‘c’ ] = » ;
$array [ ‘d’ ] = » ;
$array [ ‘e’ ] = » ;

// all given keys a,b,c exists in the supplied array
var_dump ( array_keys_exists ([ ‘a’ , ‘b’ , ‘c’ ], $array )); // bool(true)

function array_keys_exists (array $keys , array $array ): bool
$diff = array_diff_key ( array_flip ( $keys ), $array );
return count ( $diff ) === 0 ;
>

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

// use:
$exists = array_key_exists ( $key3 , $arr [ $key1 ][ $key2 ]??[]) ;

I took hours for me to debug, and I finally recognized that,

You have to reset the $array before using array_key_exists
reset($array);
array_key_exists($needle,$array);

  • Array Functions
    • array_​change_​key_​case
    • array_​chunk
    • array_​column
    • array_​combine
    • array_​count_​values
    • array_​diff_​assoc
    • array_​diff_​key
    • array_​diff_​uassoc
    • array_​diff_​ukey
    • array_​diff
    • array_​fill_​keys
    • array_​fill
    • array_​filter
    • array_​flip
    • array_​intersect_​assoc
    • array_​intersect_​key
    • array_​intersect_​uassoc
    • array_​intersect_​ukey
    • array_​intersect
    • array_​is_​list
    • array_​key_​exists
    • array_​key_​first
    • array_​key_​last
    • array_​keys
    • array_​map
    • array_​merge_​recursive
    • array_​merge
    • array_​multisort
    • array_​pad
    • array_​pop
    • array_​product
    • array_​push
    • array_​rand
    • array_​reduce
    • array_​replace_​recursive
    • array_​replace
    • array_​reverse
    • array_​search
    • array_​shift
    • array_​slice
    • array_​splice
    • array_​sum
    • array_​udiff_​assoc
    • array_​udiff_​uassoc
    • array_​udiff
    • array_​uintersect_​assoc
    • array_​uintersect_​uassoc
    • array_​uintersect
    • array_​unique
    • array_​unshift
    • array_​values
    • array_​walk_​recursive
    • array_​walk
    • array
    • arsort
    • asort
    • compact
    • count
    • current
    • end
    • extract
    • in_​array
    • key_​exists
    • key
    • krsort
    • ksort
    • list
    • natcasesort
    • natsort
    • next
    • pos
    • prev
    • range
    • reset
    • rsort
    • shuffle
    • sizeof
    • sort
    • uasort
    • uksort
    • usort
    • each

    Источник

    array_key_exists

    Функция array_key_exists() возвращает TRUE , если в массиве присутствует указанный ключ key . Параметр key может быть любым значением, которое подходит для индекса массива.

    Список параметров

    Массив с проверяемыми ключами

    Возвращаемые значения

    Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки.

    Примеры

    Пример #1 Пример использования array_key_exists()

    $search_array = array( ‘first’ => 1 , ‘second’ => 4 );
    if ( array_key_exists ( ‘first’ , $search_array )) echo «Массив содержит элемент ‘first’.» ;
    >
    ?>

    Пример #2 array_key_exists() и isset()

    isset() не возвращает TRUE для ключей массива, указывающих на NULL , а array_key_exists() возвращает.

    $search_array = array( ‘first’ => null , ‘second’ => 4 );

    // возвращает false
    isset( $search_array [ ‘first’ ]);

    // возвращает true
    array_key_exists ( ‘first’ , $search_array );
    ?>

    Примечания

    Замечание:

    Для обратной совместимости может быть использован следующий устаревший псевдоним: key_exists()

    Замечание:

    По причинам обратной совместимости array_key_exists() возвращает TRUE , если key является свойством объекта, переданным в качестве параметра array . На это поведение не стоит полагаться, и перед использованием данной функции необходимо проверять, что параметр array имеет тип array .

    Чтобы проверить, содержит ли объект какое-либо свойство, используйте функцию property_exists() .

    Смотрите также

    • isset() — Определяет, была ли установлена переменная значением отличным от NULL
    • array_keys() — Возвращает все или некоторое подмножество ключей массива
    • in_array() — Проверяет, присутствует ли в массиве значение
    • property_exists() — Проверяет, содержит ли объект или класс указанный атрибут

    Источник

    key_exists

    Функция является псевдонимом: array_key_exists() .

    User Contributed Notes

    • Функции для работы с массивами
      • array_​change_​key_​case
      • array_​chunk
      • array_​column
      • array_​combine
      • array_​count_​values
      • array_​diff_​assoc
      • array_​diff_​key
      • array_​diff_​uassoc
      • array_​diff_​ukey
      • array_​diff
      • array_​fill_​keys
      • array_​fill
      • array_​filter
      • array_​flip
      • array_​intersect_​assoc
      • array_​intersect_​key
      • array_​intersect_​uassoc
      • array_​intersect_​ukey
      • array_​intersect
      • array_​is_​list
      • array_​key_​exists
      • array_​key_​first
      • array_​key_​last
      • array_​keys
      • array_​map
      • array_​merge_​recursive
      • array_​merge
      • array_​multisort
      • array_​pad
      • array_​pop
      • array_​product
      • array_​push
      • array_​rand
      • array_​reduce
      • array_​replace_​recursive
      • array_​replace
      • array_​reverse
      • array_​search
      • array_​shift
      • array_​slice
      • array_​splice
      • array_​sum
      • array_​udiff_​assoc
      • array_​udiff_​uassoc
      • array_​udiff
      • array_​uintersect_​assoc
      • array_​uintersect_​uassoc
      • array_​uintersect
      • array_​unique
      • array_​unshift
      • array_​values
      • array_​walk_​recursive
      • array_​walk
      • array
      • arsort
      • asort
      • compact
      • count
      • current
      • end
      • extract
      • in_​array
      • key_​exists
      • key
      • krsort
      • ksort
      • list
      • natcasesort
      • natsort
      • next
      • pos
      • prev
      • range
      • reset
      • rsort
      • shuffle
      • sizeof
      • sort
      • uasort
      • uksort
      • usort
      • each

      Источник

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