PHP 5.6.0 released

get_defined_constants

(PHP 4 >= 4.1.0, PHP 5)

get_defined_constantsReturns 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

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());
?>

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] => 2047
    [TRUE] => 1
)

See Also

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User Contributed Notes 4 notes

up
2
Bob
6 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
1
Anonymous
8 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
1
me at gogogadgetscott dot info
9 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
-1
bimal at sanjaal dot com
1 year ago
Though the syntax editors mark the following as error, it executes successfully under PHP, as you desire.

<?php
$user_defined_constants
=get_defined_constants(true)['user'];
print_r($user_defined_constants);
?>

No errors/warnings seen.
Only the special thing here is, you are passing true to the function, and extracting the result's 'user' index directly.
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