International PHP Conference Berlin 2025

    get_defined_constants

    (PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

    get_defined_constants — すべての定数の名前とその値を連想配列として返す

    説明

    get_defined_constants(bool $categorize = false): array

    現在定義されている全ての定数の名前と値を返します。返される値には、 拡張モジュールにより作成された定数や define() 関数で作成された定数も含まれます。

    パラメータ

    categorize

    これを渡すと、この関数は多次元の配列を返すようになります。 最初の次元のキーがカテゴリとなり、 そのカテゴリ内の定数とその値が下位レベルに格納されます。

    <?php
    define    ("MY_CONSTANT", 1);
    print_r(get_defined_constants(true));
    ?>

    上の例の出力は、 たとえば以下のようになります。

    Array
(
    [Core] => Array
        (
            [E_ERROR] => 1
            [E_WARNING] => 2
            [E_PARSE] => 4
            [E_NOTICE] => 8
            [E_CORE_ERROR] => 16
            [E_CORE_WARNING] => 32
            [E_COMPILE_ERROR] => 64
            [E_COMPILE_WARNING] => 128
            [E_USER_ERROR] => 256
            [E_USER_WARNING] => 512
            [E_USER_NOTICE] => 1024
            [E_ALL] => 2047
            [TRUE] => 1
        )

    [pcre] => Array
        (
            [PREG_PATTERN_ORDER] => 1
            [PREG_SET_ORDER] => 2
            [PREG_OFFSET_CAPTURE] => 256
            [PREG_SPLIT_NO_EMPTY] => 1
            [PREG_SPLIT_DELIM_CAPTURE] => 2
            [PREG_SPLIT_OFFSET_CAPTURE] => 4
            [PREG_GREP_INVERT] => 1
        )

    [user] => Array
        (
            [MY_CONSTANT] => 1
        )

)

    戻り値

    定数名 => 定数値 の配列の配列を返します。 オプションで、その定数を定義している拡張モジュール名ごとにグループ化することもできます。

    例

    例1 get_defined_constants() の例

    <?php
    print_r    (get_defined_constants());
    ?>

    上の例の出力は、 たとえば以下のようになります。

    Array
(
    [E_ERROR] => 1
    [E_WARNING] => 2
    [E_PARSE] => 4
    [E_NOTICE] => 8
    [E_CORE_ERROR] => 16
    [E_CORE_WARNING] => 32
    [E_COMPILE_ERROR] => 64
    [E_COMPILE_WARNING] => 128
    [E_USER_ERROR] => 256
    [E_USER_WARNING] => 512
    [E_USER_NOTICE] => 1024
    [E_ALL] => 2047
    [TRUE] => 1
)

    参考

    Found A Problem?

    Learn How To Improve This Page • Submit a Pull Request • Report a Bug
    ＋add a note

    User Contributed Notes 5 notes

    up
    23
    Bob
    16 years ago
    Add this method to your class definition if you want an array of class constants (get_defined_constants doesn't work with class constants as Peter P said above):

    <?php
    public function get_class_constants()
    {
    $reflect = new ReflectionClass(get_class($this));
    return     $reflect->getConstants());
    }
    ?>

    You could also override stdObject with it so that all your classes have this method
    up
    12
    R4FC0R3
    6 years ago
    If you want to access directly on one category, just use:

    <?php

    print_r    (get_defined_constants(true)['Core']);

    ?>

    you can replace 'Core' by the category you wish (e.g. user):

    <?php

    print_r    (get_defined_constants(true)['user']);

    ?>

    Warning: only use this on development side
    up
    9
    Anonymous
    18 years ago
    If you want to filter through and return only the prefix for your constants (i.e. you have constants with a naming scheme), then you can use this quick little function. It comes in handy for debugging.

    <?php
    function returnConstants ($prefix) {
    foreach (    get_defined_constants() as $key=>$value)
    if (    substr($key,0,strlen($prefix))==$prefix) $dump[$key] = $value;
    if(empty(    $dump)) { return "Error: No Constants found with prefix '".$prefix."'"; }
    else { return     $dump; }
    }
    ?>

    Example:

    <?php
    define    ("SITENAME_OPTION_ONE",true);
    define("SITENAME_OPTION_TWO",false);
    define("SITENAME_URL","foo");

    print_r(returnConstants("SITENAME_OPTION"));
    ?>

    Will return:

    Array
    (
    [SITENAME_OPTIONONE] => 1
    [SITENAME_OPTIONTWO] =>
    )
    up
    5
    me at gogogadgetscott dot info
    19 years ago
    <?php
    /**
    * Convert constant value into string name.
    *
    * @param mixed Constant value.
    * @return string Constant name.
    * @access public
    */
    function sch_get_consant($value)
    {
    $constants = get_defined_constants();
    $name = array_search($value, $constants, TRUE);
    return     $name;
    }
    ?>
    up
    -3
    S-Tian
    2 years ago
    If you want to create a static method that you can copy and paste into each class you have constants created, you can use:

    <php
    public static function get_class_constants(): array
    {
    $reflect = new ReflectionClass(self::class);

    return $reflect->getConstants();
    }
    ?>
    ＋add a note
    To Top