{"id":159,"date":"2021-03-08T03:27:59","date_gmt":"2021-03-08T03:27:59","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=159"},"modified":"2025-04-07T12:38:54","modified_gmt":"2025-04-07T12:38:54","slug":"php-magic-constants","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/php-magic-constants\/","title":{"rendered":"PHP Magic Constants"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn about PHP magic constants that hold values change depending on where they are used.<\/p>\n\n\n\n

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

In PHP, regular constants<\/a> store values that don’t change during the execution of the script. PHP resolves the constants defined by the define()<\/code> function at runtime and resolves the constants defined by the const<\/code> keyword at compile time. <\/p>\n\n\n\n

Besides the regular constants, PHP has some constants whose values change depending on where you use them. For example, the __LINE__<\/code> constant returns the current line number of the current script. <\/p>\n\n\n\n

These constants are known as magic constants. Unlike regular constants, PHP resolves the magic constants at runtime.<\/p>\n\n\n\n

The following table illustrates the magic constants in PHP:<\/p>\n\n\n\n

Name<\/th>Description<\/th><\/tr><\/thead>
__LINE__<\/code><\/td>Return the current line number of the file.<\/td><\/tr>
__FILE__<\/code><\/td>Return the full path and filename of the file or include<\/a>.<\/td><\/tr>
__DIR__<\/code><\/td>Return the directory of the file or include. It’s equivalent to dirname(__FILE__)<\/code>. The __DIR__ doesn’t have a trailing slash (\/<\/code>) unless it’s the root directory.<\/td><\/tr>
__FUNCTION__<\/code><\/td>Return function name, or {closure}<\/code> for anonymous functions<\/a>.<\/td><\/tr>
__CLASS__<\/code><\/td>Return the class name<\/a> that also includes the namespace.<\/td><\/tr>
__TRAIT__<\/code><\/td>Return the trait<\/a> name that includes the namespace<\/td><\/tr>
__METHOD__<\/code><\/td>Return the name of the current instance method.<\/td><\/tr>
__NAMESPACE__<\/code><\/td>Return the name of the current namespace<\/a>.<\/td><\/tr>
ClassName::class<\/code><\/td>Return the fully qualified class name.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

PHP magic constant example #<\/a><\/h2>\n\n\n\n

The following example shows the values of the above magic constants:<\/p>\n\n\n

<?php<\/span>\n\nnamespace<\/span> App<\/span>;\n\nclass<\/span> HttpRequest<\/span>\n<\/span>{\n    public<\/span> function<\/span> __construct<\/span>()<\/span>\n    <\/span>{\n        echo<\/span> 'The current class name is '<\/span> .  __CLASS__<\/span> . '<br>'<\/span>;\n    }\n    public<\/span> function<\/span> isPost<\/span>()<\/span>\n    <\/span>{\n        echo<\/span> 'The current method is '<\/span> . __METHOD__<\/span> . '<br>'<\/span>;\n        \n        return<\/span> $_SERVER['REQUEST_METHOD'<\/span>];\n    }\n}\n\n$request = new<\/span> HttpRequest();\n\n$request->isPost();\n\necho<\/span> 'The current namespace is '<\/span> . __NAMESPACE__<\/span> . '<br>'<\/span>;\necho<\/span> 'The fully qualified class name is '<\/span>  . HttpRequest::class . '<br>'<\/span>;\necho<\/span> 'The current file is '<\/span> . __FILE__<\/span> . '<br>'<\/span>;\necho<\/span> 'The current line is '<\/span> . __LINE__<\/span> . '<br>'<\/span>;\necho<\/span> 'The current directory is '<\/span> . __DIR__<\/span>  . '<br>'<\/span>;<\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
The current class name is App\\HttpRequest\nThe current method is App\\HttpRequest::isPost\nThe current namespace is App\nThe fully qualified class name is App\\HttpRequest\nThe current file is C:\\xampp\\htdocs\\phptutorial\\class.php\nThe current line is 29\nThe current directory is C:\\xampp\\htdocs\\phptutorial\\<\/code><\/span>Code language:<\/span> plaintext<\/span> (<\/span>plaintext<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
  • PHP magic constants hold values resolved at runtime, not compile time.<\/li>
  • The values of the magic constants change depending on where they’re used.<\/li><\/ul>\n
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    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
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    <\/div>\n\t\t\t\n\t\t\t