{"id":1833,"date":"2021-05-22T04:36:18","date_gmt":"2021-05-22T04:36:18","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=1833"},"modified":"2025-04-06T07:53:39","modified_gmt":"2025-04-06T07:53:39","slug":"php-__dir__","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/php-__dir__\/","title":{"rendered":"PHP __DIR__"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about how to use the PHP __DIR__<\/code> magic constant when including a PHP file.<\/p>\n\n\n\n

Introduction to the PHP __DIR__ magic constant #<\/a><\/h2>\n\n\n\n

PHP 5.3 introduced a new magic constant called __DIR__<\/code>. When you reference the __DIR__<\/code> inside a file, it returns the directory of the file. The __DIR__<\/code> doesn’t include a trailing slash, e.g., \/<\/code> or \\<\/code> except it’s a root directory.<\/p>\n\n\n\n

When you use the __DIR__<\/code> inside an include, the __DIR__<\/code> returns the directory of the included file.<\/p>\n\n\n\n

Technically speaking, the __DIR__<\/code> is equivalent to the dirname(__FILE__)<\/code>. However, using the __DIR__<\/code> is more concise than the dirname(__FILE__)<\/code>.<\/p>\n\n\n\n

Simple PHP __DIR__example #<\/a><\/h2>\n\n\n\n

Suppose you have the following directory structure:<\/p>\n\n\n

.\n\u251c\u2500\u2500 inc\n\u2502   \u251c\u2500\u2500 footer.php      \n\u2502   \u2514\u2500\u2500 header.php\n\u2514\u2500\u2500 index.php<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The header.php<\/code> contains the code of the header part:<\/p>\n\n\n
<!DOCTYPE html>\n<html lang=\"en\"<\/span>>\n<head>\n    <meta charset=\"UTF-8\"<\/span>>\n    <meta name=\"viewport\"<\/span> content=\"width=device-width, initial-scale=1.0\"<\/span>>\n    <title>PHP __DIR__<\/span> Demo<\/title>\n<\/head>\n<body><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The footer.php<\/code> contains the code of the footer part. It also shows the value of the __DIR__<\/code> constant:<\/p>\n\n\n
<p><?php<\/span> echo<\/span> __DIR__<\/span> ?><\/span><\/p>\n<\/body>\n<\/html><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The index.php includes both header.php<\/code> and footer.php<\/code> files. It also shows the value of the __DIR__<\/code> constant:<\/p>\n\n\n
<?php<\/span> require<\/span> 'inc\/header.php'<\/span> ?><\/span>\n<h1>Home<\/h1>\n<p><?php<\/span> echo<\/span> __DIR__<\/span> ?><\/span><\/p>\n<?php<\/span> require<\/span> 'inc\/footer.php'<\/span> ?><\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The following shows the output on the web browser:<\/p>\n\n\n
Home\nC:\\xampp\\htdocs\\web\nC:\\xampp\\htdocs\\web\\inc<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The __DIR__<\/code> in the index.php<\/code> returns the current directory of the index.php<\/code> C:\\xampp\\htdocs\\web<\/code> while the __DIR__<\/code> in the footer.php<\/code> file returns the directory of the footer.php<\/code> file C:\\xampp\\htdocs\\web\\inc<\/code>.<\/p>\n\n\n\n
Why using PHP __DIR__ #<\/a><\/h2>\n\n\n\n
Suppose that you have a project with the following directory structure:<\/p>\n\n\n
.\n\u251c\u2500\u2500 admin\n\u2502   \u2514\u2500\u2500 dashboard\n\u2502       \u2514\u2500\u2500 index.php\n\u251c\u2500\u2500 config\n\u2502   \u2514\u2500\u2500 app.php\n\u251c\u2500\u2500 inc\n\u2502   \u251c\u2500\u2500 footer.php\n\u2502   \u2514\u2500\u2500 header.php\n\u2514\u2500\u2500 public<\/span>\n    \u2514\u2500\u2500 index.php<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The config\/app.php<\/code> contains the application’s configuration:<\/p>\n\n\n
<?php<\/span>\n\ndefine('APP_NAME'<\/span>, 'My Awesome App'<\/span>);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The header.php<\/code> contains the header part of a page. It also includes the config\/app.php<\/code> file and uses the APP_NAME<\/code> constant:<\/p>\n\n\n
<?php<\/span> require<\/span> '..\/config\/app.php'<\/span> ?><\/span>\n<!DOCTYPE html>\n<html lang=\"en\"<\/span>>\n<head>\n    <meta charset=\"UTF-8\"<\/span>>\n    <meta name=\"viewport\"<\/span> content=\"width=device-width, initial-scale=1.0\"<\/span>>\n    <title><?php<\/span> echo<\/span> APP_NAME ?><\/span><\/title>\n<\/head>\n<body><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The footer.php<\/code> contains the closing tags of the body<\/code> and html<\/code> elements:<\/p>\n\n\n
<\/body>\n<\/html><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The public\/index.php<\/code> file includes both header.php<\/code> and footer.php<\/code> files:<\/p>\n\n\n
<?php<\/span> require<\/span> '..\/inc\/header.php'<\/span> ?><\/span>\n<h1>Home<\/h1>\n<?php<\/span> require<\/span> '..\/inc\/footer.php'<\/span>?><\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
If you navigate to the http:\/\/localhost\/web\/public\/index.php<\/code>, you’ll see the following output when you view the source of the page:<\/p>\n\n\n
<!DOCTYPE html>\n<html lang=\"en\"<\/span>>\n<head>\n    <meta charset=\"UTF-8\"<\/span>>\n    <meta name=\"viewport\"<\/span> content=\"width=device-width, initial-scale=1.0\"<\/span>>\n    <title>My Awesome App<\/title>\n<\/head>\n<body>\n    <h1>Dashboard<\/h1>\n<\/body>\n<\/html><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
So the index.php<\/code> page in the public<\/code> directory works as expected.<\/p>\n\n\n\n
The index.php<\/code> in the admin\/dashboard<\/code> also includes the header.php<\/code> and footer.php<\/code> files:<\/p>\n\n\n
<?php<\/span> require<\/span> '..\/..\/inc\/header.php'<\/span> ?><\/span>\n<h1>Dashboard<\/h1>\n<?php<\/span> require<\/span> '..\/..\/inc\/footer.php'<\/span> ?><\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
When you browse the page http:\/\/localhost\/web\/admin\/dashboard\/index.php<\/code>, you’ll see the following error:<\/p>\n\n\n
Warning: require<\/span>(..\/config\/app.php): failed to open stream: No such file or<\/span> directory in C:\\xampp\\htdocs\\web\\inc\\header.php on line 1<\/span>\n\nFatal error: require<\/span>(): Failed opening required '..\/config\/app.php'<\/span> (include_path='\\xampp\\php\\PEAR'<\/span>) in C:\\xampp\\htdocs\\web\\inc\\header.php on line 1<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The error message shows that the header.php cannot load the '..\/config\/app.php'<\/code> file.<\/p>\n\n\n\n
When the index.php<\/code> in the admin\/dashboard<\/code> directory loads the code from the header.php<\/code>, it’ll find the config\/app.php<\/code> inside the admin<\/code> directory, not root<\/code> directory.<\/p>\n\n\n\n
Since the admin<\/code> directory doesn’t have the config\/app.php<\/code> file, PHP issues an error.<\/p>\n\n\n\n
To fix this issue, you can use the __DIR__<\/code> when you include the config.php<\/code> in the header.php<\/code> file like this:<\/p>\n\n\n
<?php<\/span>  require<\/span> __DIR__<\/span>. '\/..\/config\/app.php'<\/span> ?><\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The index.php<\/code> in the admin\/dashboard<\/code> will work correctly.<\/p>\n\n\n\n
This is because when PHP loads the inc\/header.php<\/code> file from either public\/index.php<\/code> or admin\/dashboard\/index.php<\/code>, the __DIR__<\/code> inside the inc\/header.php<\/code> always returns C:\\xampp\\htdocs\\web\\inc<\/code>.<\/p>\n\n\n\n
Therefore, it’s a good practice to use the __DIR__<\/code> constant when you include a file.<\/p>\n\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
    \n
  • PHP __DIR__<\/code> returns the directory of a file or the directory of the include file when the file is used as an include.<\/li>\n\n\n\n
  • Use __DIR__<\/code> when you include a file.<\/li>\n<\/ul>\n
    \n\t
    \n\t\t
    Did you find this tutorial useful?<\/div>\n\t\t
    \n\t\t\t\n\t\t\t\t\n\t\t\t\t\t<\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t Yes <\/span>\n\t\t\t<\/button>\n\n\t\t\t\n\t\t\t\t\n\t\t\t\t\t<\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t No <\/span>\n\t\t\t<\/button>\n\t\t<\/div>\n\t<\/header>\n\n\t
    \n\t\t
    \n\t\t\t
    <\/div>\n\t\t\t\n\t\t\t