definePHP ManualPrevNextdefinedefine -- Defines a named constant.Descriptionint define(string name, mixed value, int [case_insensitive] ); Defines a named constant, which is similar to a variable except: Constants do not have a dollar sign '$' before them; Constants may be accessed anywhere without regard to variable scoping rules; Constants may not be redefined or undefined once they have been set; and Constants may only evaluate to scalar values. The name of the constant is given by name; the value is given by value. The optional third parameter case_insensitive is also available. If the value 1 is given, then the constant will be defined case-insensitive. The default behaviour is case-sensitive; i.e. CONSTANT and Constant represent different values. Example 1. Defining Constants 1  2 <?php 3 define ("CONSTANT", "Hello world."); 4 echo CONSTANT; // outputs "Hello world." 5 ?> 6  define() returns TRUE on success and FALSE if an error occurs. See also defined() and the section on Constants. PrevHomeNextconnection_timeoutUpdefined