PHP：如何避免重新声明函数？

问题描述

我倾向于得到如下错误：
$ b

我怎样才能避免这个错误？是否有可能在声明它之前创建一个IF子句来检查函数是否被声明了？

使用或 as反对 include 或 require 包含您的函数的文件。

$ b

_once code> include 和 require 将强制PHP检查文件是否已经包含/必需，如果是，则不是 include / 需要它，从而防止'无法重新声明x函数... '致命错误。

I tend to get errors such as:

how can I avoid the error? Is it possible to create a IF-clause to check whether a function is declared before declaring it?

解决方案

Use require_once or include_once as opposed to include or require when including the files that contain your functions.

The _once siblings of include and require will force PHP to check if the file has already been included/required, and if so, not include/require it again, thereby preventing 'cannot redeclare x function...' fatal errors.

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