define――定义常量,若定义true，则读取时不区分大小写
bool define( string name, mixed value [, bool case_insensitive])
常量只能包含标量数据（boolean
，integer
，float
和 string
）。
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."
?
?
========================================
constant()――读取常量
mixed constant ( string name)
?
define
(
"MAXSIZE"
,
100
);
echo
MAXSIZE
;
echo
constant
(
"MAXSIZE"
);
// same thing as the previous line
?
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
?
defined――判断常量是否定义
?
bool defined ( string name)
?
if (
defined
(
'CONSTANT'
)) {
????echo
CONSTANT
;
}
?
======================================================
?
预定义常量
?
__FILE__?? 取得文件的物理地址? 注：左右各2条下划线
?
echo __FILE__? ?? //C:\wamp\www\T1\1.php
?
?
?
?