还有require和include_once.

所以你的问题应该是...

So your question should be...

1. 我应该什么时候使用 require 与 include?
2. 我应该什么时候使用 require_once 与 require

1. When should I use require vs. include?
2. When should I use require_once vs. require

此处描述了 1 的答案.

require() 函数与 include() 相同，只是它处理错误的方式不同.如果发生错误，include() 函数会生成警告，但脚本将继续执行.require() 产生致命错误，脚本将停止.

The require() function is identical to include(), except that it handles errors differently. If an error occurs, the include() function generates a warning, but the script will continue execution. The require() generates a fatal error, and the script will stop.

可以在此处找到 2 的答案.

The answer to 2 can be found here.

require_once() 语句与 require() 相同，除了 PHP 会检查文件是否已经被包含，如果是，则不再包含(要求)它.

The require_once() statement is identical to require() except PHP will check if the file has already been included, and if so, not include (require) it again.