defined(3) [php man page]

DEFINED(3)								 1								DEFINED(3)

defined - Checks whether a given named constant exists

SYNOPSIS

       bool defined (string  $name)

DESCRIPTION

	Checks whether the given constant exists and is defined.

       Note

	       If  you	want  to  see if a variable exists, use isset(3) as defined(3) only applies to constants. If you want to see if a function
	      exists, use function_exists(3).

PARAMETERS

	      o $name
		- The constant name.

RETURN VALUES

	Returns TRUE if the named constant given by $name has been defined, FALSE otherwise.

EXAMPLES

       Example #1

	      Checking Constants

	      <?php
	      /* Note the use of quotes, this is important.  This example is checking
	       * if the string 'TEST' is the name of a constant named TEST */
	      if (defined('TEST')) {
		  echo TEST;
	      }
	      ?>

SEE ALSO

       define(3), constant(3), get_defined_constants(3), function_exists(3), The section on Constants.

PHP Documentation Group 														DEFINED(3)

GET_DEFINED_CONSTANTS(3)						 1						  GET_DEFINED_CONSTANTS(3)

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

SYNOPSIS

       array get_defined_constants ([bool  $categorize = false])

DESCRIPTION

	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(3) function.

PARAMETERS

	      o $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,  pre- |
       |	| viously  internal. On Windows, the Core Constants |
       |	| are categorized under mhash.			    |
       |	|						    |
       |5.2.11	|						    |
       |	|						    |
       |	|  The $categorize parameter now operates appropri- |
       |	| ately.  Previously, the $categorize parameter was |
       |	| interpreted as !is_null($categorize), making	any |
       |	| value  other	than NULL force the constants to be |
       |	| categorized.					    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES

       Example #1

	      get_defined_constants(3) 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

       defined(3), get_loaded_extensions(3), get_defined_functions(3), get_defined_vars(3).

PHP Documentation Group 												  GET_DEFINED_CONSTANTS(3)