PHP Manual: Returns an associative array with the names of all the constants and their values

Description

array get_defined_constants ([ bool $categorize = false ] )

Returns the names and values of all the constants currently defined. This includes those created by extensions as well as those created with the define function.

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] => 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
        )

)

Return Values

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

Changelog

Version	Description
5.3.1	Windows only: Core constants are categorized under Core, previously mhash.
5.3.0	Core constants are categorized under Core, previously internal. On Windows, the Core Constants are categorized under mhash.
5.2.11	The `categorize` parameter now operates appropriately. Previously, the `categorize` parameter was interpreted as !is_null($categorize), making any value other than `NULL` force the constants to be categorized.
5.0.0	The `categorize` parameter was added.

Examples

Example #1 get_defined_constants Example


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