Code reuse through Include and Require functions_PHP Tutorial

If you have built Web sites of various sizes, you must have a deep understanding of the importance of reusing code segments, whether it is HTML or PHP code blocks. For example, if you need to modify the footer containing copyright information once a year, and you have 1,000 Web pages (even 10), manual operation will make you miserable. With PHP, you can use different functions to help you reuse code. The exact functions you use depend on what you plan to reuse. The main function is as follows: * include() and include_once() * require() and require_once() The include() function includes the given file and checks it. For example: include(/home/me/myfile); Any code in the included file will be executed within the variable scope, which is equivalent to where the function include() appears in the parent code. You can include static files on a server or object files on another server by combining the include() and fopen() functions. The include_once() function performs the same function as the include() function, only checking whether the code in the file has been included in the current script. If the code is already included in the script, the function no longer includes the corresponding file. The require() function replaces itself with the contents of the given file. This replacement process occurs when the PHP engine compiles your code rather than during execution, unlike include(), which is evaluated first. The require() function is more used for static elements, while the include() function is mainly used for dynamic elements. Similar to include_once(), the require_once() function checks whether the given code has already been inserted into the document. If the code already exists, the given code will not be inserted into the document again. It is recommended to use the require function for information such as copyright, static text and other elements without variables. Elements that rely on other scripts to implement their own content should also use the require function, for example:

[a lot of content] //插入版权信息 require(/home/me/mycopyright); ?> On the other hand, the include() function is often used to put function libraries or similar libraries outside the script: //获取我的函数库 include(/home/me/myfunctions); // 使用我的函数执行PHP程序？> [a lot of content] The next natural question is: "Where do the included or required files come from?" The short answer is: "Your system." However, just some code snippets sometimes contain security information such as a database connection with an identified username and password. Obviously you don't want these things to become part of the documentation and be made public. You can place included files (included or required) anywhere on the system, as long as the user's PHP can access these files. You can also give these files any extension you wish, or no extension at all. Use the include() and require() functions to make elements that are common or frequently changing on a Web site concrete. This will also make the system architecture easier to handle when upgrades are needed.

http://www.bkjia.com/PHPjc/509179.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/509179.htmlTechArticleIf you have made Web sites of various sizes, you will definitely have a deep understanding of the importance of reusing code snippets. Be it HTML or PHP code blocks. For example, a page containing copyright information needs to be modified once a year...