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PHP Manual

Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

The following constants are meant to be used with parse_url() and are available since PHP 5.1.2.

PHP_URL_SCHEME ( integer )
PHP_URL_HOST ( integer )
PHP_URL_PORT ( integer )
PHP_URL_USER ( integer )
PHP_URL_PASS ( integer )
PHP_URL_PATH ( integer )
PHP_URL_QUERY ( integer )
PHP_URL_FRAGMENT ( integer )

URLs
PHP Manual