PHP include_ once

PHP include_ once is used to import a PHP file. The usage is similar to include (almost the same), but the difference is that when the imported file is repeated, include will still add the file to its own file repeatedly, and include_once will not do this, just like once means it will only be introduced once.

If you want other files included in the main file to be included only once, use include_once! In addition, you must pay attention to the skills of this type of include file, that is, the operating system's case recognition will have an impact on the execution of the program. Please refer to the part of the description of require_once .

Supplementary note: If you want to stop when there is a problem with the execution of the included program, you can refer to: PHP require .