Table of Contents
PHP define() 函数
定义和用法
例子 2
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PHP define() 函数

Jun 13, 2016 am 11:52 AM
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PHP define() 函数

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定义和用法

define() 函数定义一个常量。

常量类似变量,不同之处在于:

  • 在设定以后,常量的值无法更改
  • 常量名不需要开头的美元符号 ($)
  • 作用域不影响对常量的访问
  • 常量值只能是字符串或数字

语法:

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define(name,value,case_insensitive)
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参数描述
name 必需。规定常量的名称。
value 必需。规定常量的值。
case_insensitive

可选。规定常量的名称是否对大小写敏感。

若设置为 true,则对大小写不敏感。默认是 false(大小写敏感)。

例子

例子 1

定义一个大小写敏感的常量:

<?php <code>define("GREETING","Hello world!");echo constant("GREETING");?>
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输出:

Hello world!
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例子 2

定义一个大小写不敏感的常量:

<?php <code>define("GREETING","Hello world!",TRUE);echo constant("greeting");?>
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输出:

Hello world!
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Copy after login

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