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# define

define -- Defines a named constant.

## Description

`int 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.

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