Php require function syntax

Include() and Require() Function in PHP

Require and Include function in PHP; In this tutorial, you will learn learn require and include function of PHP with these function definitions, syntax, parameters, differences,s and examples.

When it comes to including files in PHP, two common methods are used: include() and require() . Both these functions are used to include other PHP files, but there are some differences between them that developers should understand.

The include() function is used to include a PHP file into another PHP file. If the file cannot be found or there is an error, a warning message is displayed, but the script will continue to run. The require() function works the same way as include() , but if the file cannot be found or there is an error, it will halt the script and display a fatal error.

So, when should you use include() and when should you use require() ? The answer depends on how critical the included file is to the operation of your script. If the included file contains non-critical code, such as a header or footer, you should use include() . If the included file contains critical code, such as database connections or functions that are essential to the operation of your script, you should use require() .

It is also important to note that the include() and require() functions have variants, such as include_once() and require_once() . These functions are used to include files only once, even if they are called multiple times in a script. This can help prevent issues with duplicate function or class definitions.

Include() and Require() Function in PHP

• Include PHP Function
• Require PHP Function
• Example 1: How to use include() and require() in PHP
• Question 1:- What is the difference between include and require in PHP?

Include PHP Function

The include() function is used to include a file in a PHP script. This function includes the specified file and executes its code within the current script. If the specified file is not found, a warning message is displayed, but the script continues to execute.

Note:- The PHP include() function, it will produce a warning error, without halt the execution of PHP script.

Syntax:-

Here is the syntax for the include() function:

Example of include() function

The example of PHP include() function is the following:

  //include file using include() function  
include() function Example
   

Require PHP Function

The require() function is similar to the include() function in that it is used to include a file in a PHP script. However, there is one important difference between the two functions. If the specified file is not found, the require() function will produce a fatal error and stop the script from executing.

Note:- The PHP require() function, it will produce a fatal error and halt the execution of php script.

Syntax:-

Here is the syntax for the require() function:

Example of Require() function

The example of PHP require() function is the following:

  //require file using require() function  
include() function Example
   

Example 1: How to use include() and require() in PHP

Here is an example of how to use include() and require() in PHP:

// Using include() to include a non-critical file include('header.php'); echo "Welcome to my website!"; include('footer.php'); // Using require() to include a critical file require('database.php'); $db = new Database();

In the above example, header.php and footer.php are included using include() , since they contain non-critical code such as HTML markup. database.php , on the other hand, is included using require() , since it contains critical code such as the database connection.

Question 1:- What is the difference between include and require in PHP?

The main difference between include and require is how they handle errors when the specified file is not found. The include() function will continue to execute the script even if the file is not found, whereas the require() function will produce a fatal error and stop the script from executing.

When to use include

The include() function is useful when you want to include a file in a PHP script, but you don’t want the script to stop executing if the file is not found. For example, you may want to include a header or footer file in a PHP script, but if the file is not found, you can still display the content of the page.

When to use require

The require() function is useful when you want to include a file in a PHP script, but you want the script to stop executing if the file is not found. For example, you may want to include a configuration file in a PHP script, but if the file is not found, the script cannot run properly and should stop executing.

Conclusion

the include() and require() functions are both useful for including PHP files into other PHP files. The key difference between them is how they handle errors when the file cannot be found or there is an error in the included code. Developers should choose the appropriate function based on the criticality of the included file to their script’s operation.

And the difference between include and require in PHP comes down to how they handle errors when the specified file is not found. The include() function will continue to execute the script, while the require() function will produce a fatal error and stop the script from executing. Use include() when you want to include a file but don’t want the script to stop executing if the file is not found. Use require() when you want to include a file, but you want the script to stop executing if the file is not found.

Recommended PHP Tutorial:

1. Autocomplete Search Box in PHP MySQL
2. Compare Arrays PHP | PHP array_diff() Function
3. Get, Write, Read, Load, JSON File from Url PHP
4. Functions: Remove First Character From String PHP
5. Remove Specific/Special Characters From String In PHP
6. How to Replace First and Last Character From String PHP
7. Reverse String in PHP
8. Array Push, POP PHP | PHP Array Tutorial
9. PHP Search Multidimensional Array By key, value and return key
10. json_encode()- Convert Array To JSON | Object To JSONPHP
11. PHP remove duplicates from multidimensional array
12. PHP Remove Duplicate Elements or Values from Array PHP
13. Get Highest Value in Multidimensional Array PHP
14. PHP Get Min or Minimum Value in Array

Author Admin

My name is Devendra Dode. I am a full-stack developer, entrepreneur, and owner of Tutsmake.com. I like writing tutorials and tips that can help other developers. I share tutorials of PHP, Python, Javascript, JQuery, Laravel, Livewire, Codeigniter, Node JS, Express JS, Vue JS, Angular JS, React Js, MySQL, MongoDB, REST APIs, Windows, Xampp, Linux, Ubuntu, Amazon AWS, Composer, SEO, WordPress, SSL and Bootstrap from a starting stage. As well as demo example.

Источник

PHP Include Files

The include (or require ) statement takes all the text/code/markup that exists in the specified file and copies it into the file that uses the include statement.

Including files is very useful when you want to include the same PHP, HTML, or text on multiple pages of a website.

PHP include and require Statements

It is possible to insert the content of one PHP file into another PHP file (before the server executes it), with the include or require statement.

The include and require statements are identical, except upon failure:

• require will produce a fatal error (E_COMPILE_ERROR) and stop the script
• include will only produce a warning (E_WARNING) and the script will continue

So, if you want the execution to go on and show users the output, even if the include file is missing, use the include statement. Otherwise, in case of FrameWork, CMS, or a complex PHP application coding, always use the require statement to include a key file to the flow of execution. This will help avoid compromising your application’s security and integrity, just in-case one key file is accidentally missing.

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

Syntax

PHP include Examples

Example 1

Assume we have a standard footer file called «footer.php», that looks like this:

To include the footer file in a page, use the include statement:

Example

Welcome to my home page!

Some text.

Some more text.

Example 2

Assume we have a standard menu file called «menu.php»:

All pages in the Web site should use this menu file. Here is how it can be done (we are using a element so that the menu easily can be styled with CSS later):

Example

Welcome to my home page!

Some text.

Some more text.

Example 3

Assume we have a file called «vars.php», with some variables defined:

Then, if we include the «vars.php» file, the variables can be used in the calling file:

Example

Welcome to my home page!

echo «I have a $color $car.»;
?>

PHP include vs. require

The require statement is also used to include a file into the PHP code.

However, there is one big difference between include and require; when a file is included with the include statement and PHP cannot find it, the script will continue to execute:

Example

Welcome to my home page!

echo «I have a $color $car.»;
?>

If we do the same example using the require statement, the echo statement will not be executed because the script execution dies after the require statement returned a fatal error:

Example

Welcome to my home page!

echo «I have a $color $car.»;
?>

Use require when the file is required by the application.

Use include when the file is not required and application should continue when file is not found.

Источник

Подключение файлов

Способность вызывать сценарий из отдельного файла по его имени называется в PHP подключением файлов. Подключают PHP-сценарии, любые текстовые файлы или HTML-страницы.

Зачем разделять и подключать PHP-сценарии

PHP-разработчики дробят исходный код проекта на отдельные сценарии, чтобы было проще работать. Если написать код в одном файле, сценарий станет необъятным, и ориентироваться будет невозможно.

Если вынести повторяющиеся блоки кода в отдельные сценарии, то появится возможность повторно использовать один код в разных файлах и подключать его только по требованию.

Например, пользовательские функции удобно объявлять в отдельном сценарии, а затем подключать там, где эти функции понадобились.

Способы подключения файлов — require и require_once

Для подключения файлов в PHP есть две языковые конструкции: require и require_once . Отличия между ними минимальны. Оба этих ключевых слова подключают файл с указанным именем и вызывают ошибку, если данный файл не существует.

👉 Особенность работы require_once — он позволяет подключать файл только один раз, даже если вызывать инструкцию несколько раз с одним именем файла.

Примеры подключения файлов

Рассмотрим, как подключить один сценарий внутри другого. Для этого воспользуемся инструкцией require . Предположим, у нас есть два сценария: index.php и sub.php .

В файле index.php находится код, который подключит сценарий sub.php :

Интересный факт: require можно использовать как ключевое слово, либо как функцию.

Результат будет одним и тем же:

Результат работы:

Привет, я содержимое из sub.php! А я - index.php! 

Что произошло? Два сценария как бы склеились в один: выполнилось все содержимое sub.php и добавилось в начало сценария index.php .

О работе с функцией require подробно рассказано в этом задании.

Абсолютные и относительные пути

При подключении файла в качестве его адреса указывают абсолютный или относительный путь.

Абсолютный путь — это полный адрес файла от корня диска. Например, /var/www/web/site/inc/sub.php

Относительный путь содержит адрес относительно текущей рабочей директории. Если сценарий лежит в папке /var/www/web/site , то для подключения файла используется такой путь: inc/sub.php

Рекомендуется всегда указывать относительные пути, чтобы сайт продолжал работать, если его переместят в другую папку.

👉 В PHP есть полезные встроенные константы, их используют в пути к подключаемым файлам.

__DIR__ — полный путь к директории с текущим сценарием.

__FILE__ — полный путь к текущему сценарию.

Видимость переменных в подключаемых сценариях

При подключении файлы склеиваются в один, поэтому и все переменные в разных сценариях тоже получают общую область видимости.

В PHP нет системы модулей, как в других языках программирования (Python, Java, ECMAScript 12). Невозможно «импортировать» отдельные переменные или функции из подключаемого сценария.

Если подключить один сценарий дважды, то переменные и функции из него тоже объявятся повторно, а это вызовет ошибку. Чтобы такого не произошло, используйте require_once .

«Доктайп» — журнал о фронтенде. Читайте, слушайте и учитесь с нами.

Источник