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

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

# 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

get_defined_constants(bool `$categorize` = `false`): array

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.

      <?phpdefine("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.

### Examples

Example #1 get_defined_constants() Example

    <?phpprint_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

- defined() - Checks whether a given named constant exists
- constant() - Returns the value of a constant
- get_loaded_extensions() - Returns an array with the names of all modules compiled and loaded
- get_defined_functions() - Returns an array of all defined functions
- get_defined_vars() - Returns an array of all defined variables