define

Description

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.