PHP Learning (6) contains code and embedded PHP

Contains code in PHP, containing code with four functions, including include_once require require_once. The main difference between include and require is that if the file does not exist, the require function throws a fatal error, and the include only throws a warning. Include include_once and require require_once, where a suffix of once indicates that the file is not referenced again if the code already contains the file. Embedded PHP in HTML embedded PHP has four ways: XML form, SGML form, ASP form, script form. Where the ASP form is not supported by default, you must modify the Asp_tags to on in the PHP configuration file [PHP.ini]. The four methods sample code are as follows: 123456789101112//XML form //SGML form //ASP Form <% echo ' Hello, world ';%>//Script form