PHP Basics (vi) Include

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Server-side include (SSI) is used to create functions, headers, footers, or elements that can be reused on multiple pages.

The include (or require) statement gets all the text/code/tags that exist in the specified file and is copied to the file that uses the include statement.

The include file is useful if you need to refer to the same PHP, HTML, or text on multiple pages of the site.

PHP include and require statements

With the include or require statement, you can insert the contents of a php file into another PHP file (before the server executes it).

The Include and require statements are the same, in addition to error handling:

Require generates a fatal error (E_COMPILE_ERROR) and stops the script

Include only generates a warning (e_warning), and the script continues

Therefore, if you want to continue execution and output the results to the user, use include if the included file is missing. Otherwise, in framework, CMS, or complex PHP application programming, always use require to reference critical files to the execution stream.

This helps improve the security and integrity of your application in the event that a critical file is accidentally lost.

The inclusion of files saves a lot of work. This means that you can create a standard header, footer, or menu file for all pages. Then, when the page header needs to be updated, you only need to update the header include file.

include ' filename '; or require ' filename ';

PHP include instance

Let's say we have a standard footer file called "footer.php", just like this:

<?phpecho "<p>copyright©2006-". Date ("Y"). "W3school.com.cn</p>";? >

To refer to this footer file in one page, use the Include statement:

Example 2

Let's say we have a standard menu file named "menu.php":

<?phpecho ' <a href= "/index.asp" > Home </a>-<a href= "/html/index.asp" >html tutorials </a>-<a href= /css/index.asp >css Tutorials </a>-<a href=/js/index.asp >javascript Tutorials </a>-<a href= "/php/ Index.asp ">php tutorial </a>";? >

This menu file is used for all pages in the site. The specific approach is (we use a <div> element so that we can easily set the style through CSS in the future):

Example 3

Suppose we have a file named "vars.php" that defines some variables:

<?php$color= ' silver '; $car = ' Mercedes-Benz Sedan ';? >

Then, if we refer to this "vars.php" file, we can use these variables in the calling file:

PHP include vs. require

The Require statement is also used to refer to a file in PHP code.

However, there is a huge difference between include and require: If a file is referenced with an include statement and PHP cannot find it, the script continues:

If we use the Require statement to complete the same case, the Echo statement will not continue because the script terminates execution after the require statement returns a critical error:

Comments:

Please use require at this time: when the file is requested by the application.

Use include at this point: when the file is not required, and the application should continue to run when the file is not found.

PHP Basics (vi) Include