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<get_current_userget_extension_funcs>
^PHP Options/Info FunctionsLast updated: Mon, 26 Oct 2026

get_defined_constants

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

get_defined_constants — Returns an associative array with the names of all the constants and their values

Description

function get_defined_constants(bool $categorize = false): array

Returns the names and values of all currently defined constants. This includes constants defined by extensions and those created using the define() function. However, it excludes magic constants, which resolve at compile time.

Parameters

categorize

Causing this function to return a multi-dimensional array with categories in the keys of the first dimension and constants and their values in the second dimension.

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

The above example will output something similar to:

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] => 30719
            [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
        )

)

Return Values

Returns an array of constant name => constant value array, optionally grouped by extension name registering the constant.

Examples

Example #1 get_defined_constants() Example

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

The above example will output something similar to:

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] => 30719
    [TRUE] => 1
)

See Also


<get_current_userget_extension_funcs>
^PHP Options/Info FunctionsLast updated: Mon, 26 Oct 2026