How to include file on PHP

There are several way to include your other PHP script files on website project. Cause a project is easier maintenance when you split several PHP code file whether your web project is large  or small.
The following list is ways to include a PHP file:

• Use php.ini to include in PHP.
• Use .htaccess to include in PHP.
• Use ini_set function.
• Use set_include_path function.
• Use include statement.

Plus, topic about supporting to including PHP code file:

• Secure files in the include  folder.
• Predefined variables.
• Absolute and Relative path.