The define() function in PHP is a powerful tool for defining constants. Whether you need to define a constant with a simple value, value of an expression, or a dynamic value, the define() function can help you accomplish this task. By following best practices for defining constants, you c...
// 错误的示例 function test() { const FOO = 'bar'; // 报错 } // 正确的示例 function test() { define('FOO', 'bar'); // 正确 } 问题:为什么const不能用于表达式? 原因:const在编译时检查,而表达式的值在运行时才能确定。 解决方法:如果需要使用表达式定义常量,可以使用define函数。 代码语言:tx...
<?php include_once "config.php" ; //ALTER TABLE `sent` MODIFY COLUMN `mean` TEXT CHARACTER SET utf8 NOT NULL; class mysql { protected $mysql; private $connect_errno; public $query_errno; public $query_error; function __construct() { $svr = MYSQL_ADDR; $user = MYSQL_USER; $pws =...
define()函数 The define() function defines a constant. define()函数的作用是:定义一个常量。 语法: define(name,value,case_insensitive) Parameter Description 参数 描述 name Required. Specifies the name of the constant(必要参数。指定常量的名称) value Required. Specifies the value of the constant(必...
Php 7 - Define: "Defines a named constant at runtime. In PHP 7, array values are also accepted."But prior PHP 7, you can maybe do this, to pass an array elsewhere using define:$to_define_array = serialize($array);define( "DEFINEANARRAY", $to_define_array );... and so ...$...
const 可以通过以下方式在类中使用: class Foo { const BAR = 1; public function myMethod() { return self::BAR; } } 你不能用 define() 做到这一点。 原文由 Marcus Lind 发布,翻译遵循 CC BY-SA 3.0 许可协议 有用 回复 撰写回答 你尚未登录,登录后可以 和开发者交流问题的细节 关注并接收问题...
5、const simply reads nicer. It's a language construct instead of a function and also is consistent with how you define constants in classes,const defines a constant in the current namespace, while define() has to be passed the full namespace name: ...
PHP定义常量如下 <?php define('TEST',1); 1. 2. 很简单 .定义了一个常量 那在内核里都做了什么? 打开zend/zend_builtin_functions.c PHP的内置函数都在这里 找到ZEND_FUNCTION(define) 代码如下 ZEND_FUNCTION(define) { char*name; intname_len; ...
https://secure.php.net/manual/en/function.define.php 本文档系腾讯云开发者社区成员共同维护,如有问题请联系 cloudcommunity@tencent.com最后更新于:2017-12-18 分享 分享
Defining a Function Functions are defined, or declared, with thefunctionkeyword. Below is the syntax for a function in JavaScript. functionnameOfFunction(){// Code to be executed} Copy The declaration begins with thefunctionkeyword, followed by the name of the function. Function names follow the...