php man page for constant

CONSTANT(3)								 1							       CONSTANT(3)

constant - Returns the value of a constant

SYNOPSIS
       mixed constant (string  $name)

DESCRIPTION
	Return the value of the constant indicated by $name.

       constant(3)  is	useful	if  you  need  to  retrieve  the value of a constant, but do not know its name. I.e. it is stored in a variable or
       returned by a function.

	This function works also with class constants.

PARAMETERS
	      o $name
		- The constant name.

RETURN VALUES
	Returns the value of the constant, or NULL if the constant is not defined.

ERRORS
/EXCEPTIONS
	An E_WARNING level error is generated if the constant is not defined.

EXAMPLES
       Example #1

	      constant(3) example

	      <?php

	      define("MAXSIZE", 100);

	      echo MAXSIZE;
	      echo constant("MAXSIZE"); // same thing as the previous line

	      interface bar {
		  const test = 'foobar!';
	      }

	      class foo {
		  const test = 'foobar!';
	      }

	      $const = 'test';

	      var_dump(constant('bar::'. $const)); // string(7) "foobar!"
	      var_dump(constant('foo::'. $const)); // string(7) "foobar!"

	      ?>

SEE ALSO
       define(3), defined(3), The section on Constants.

PHP Documentation Group 													       CONSTANT(3)