(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. It is possible to define resource constants, however it is not recommended and may cause unpredictable behavior.
If set to TRUE, the constant will be defined case-insensitive. The default behavior is case-sensitive; i.e. CONSTANT and Constant represent different values.
Note:
Case-insensitive constants are stored as lower-case.
成功时返回 TRUE， 或者在失败时返回 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."
?>