PHP require和include有什么区别? [英] What is the difference between PHP require and include?

问题描述

我知道PHP的基本用法要求，要求一次，包含一次和包含一次.但是我对何时使用它们感到困惑.

I know the basic usage of PHP require, require once, include and include once. But I am confused about when I should use them.

示例:我有3个文件，例如:settings.php，database.php和index.php.

Example: I have 3 files, eg: settings.php, database.php, and index.php.

在database.php文件中，我写道:

In database.php file, i wrote:

require_once 'settings.php';

然后在index.php中，我写道:

and then in index.php, i wrote:

require_once 'settings.php';
require_once 'database.php';

所以我两次加载settings.php，这样可以吗?使用这些功能有什么提示吗?

so I load settings.php two times, is this okay? Any tips using these functions?

推荐答案

• include包含一个文件，如果找不到该文件，则会引发警告.

  • include includes a file and throws a warning if the file was not found.

    require包含一个文件，如果找不到该文件，则会引发致命错误.

    require includes a file and throws a fatal error if the file was not found.

    include_once和require_once做同样的事情，但只有(如果尚未加载文件).

    include_once and require_once do the same thing, but only if the file was not already loaded.

    但是，对_once函数之一的需求通常表示设计不良.您应该以明确定义在什么位置包含内容的方式来构建脚本.

    However, the need for one of the _once functions is usually a sign of bad design. You should build your scripts in a way that clearly defines what gets included where.

    选择一个位置供settings.php收录-可能是index.php.无需在database.php中另外添加它.

    Choose one place for settings.php to get included - probably index.php. There should be no need to additionally include it in database.php.

    这篇关于PHP require和include有什么区别?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！