(PHP 4, PHP 5)
define — Defines a named constant
Defines a named constant at runtime.
The name of the constant.
The value of the constant; only scalar and null values are allowed. Scalar values are integer, float, string or boolean values.
If set to TRUE, the constant will be defined case-insensitive. The default behaviour is case-sensitive; i.e. CONSTANT and Constant represent different values.
如果成功则返回 TRUE，失败则返回 FALSE。
Example#1 Defining Constants
<?php
define("CONSTANT", "Hello world.");
echo CONSTANT; // outputs "Hello world."
echo Constant; // outputs "Constant" and issues a notice.
define("GREETING", "Hello you.", true);
echo GREETING; // outputs "Hello you."
echo Greeting; // outputs "Hello you."
?>