Useful PHP Predefined Constants defined by the PHP core.

PHP_VERSION - Contains a string with the current PHP version.
echo PHP_VERSION; // 5.5.3
PHP_MAXPATHLEN - The maximum length of filenames (including path) supported by this build of PHP.
echo PHP_MAXPATHLEN; // 260
PHP_OS - Contains a string that can be used to detect the operatig system PHP is running on. Some posible values:
CYGWIN_NT-5.1, Darwin (for Mac Os X), FreeBSD, HP-UX, IRIX64, Linux, NetBSD, OpenBSD, SunOS, Unix, WIN32, WINNT (for Windows NT), Windows, CYGWIN_NT-5.1, IRIX64, SunOS, HP-UX, OpenBSD.
echo PHP_OS; // WINNT
PHP_EOL - The correct 'End Of Line' symbol for the platform on which PHP is running on. Useful to add new lines in strings.
echo ''. PHP_EOL .'Next line';
__LINE__ - The current line number of the file.
// test
echo __LINE__;       // 3
__FILE__ - The full path and filename of the current php file. If used inside an include, the name of the included file is returned.
echo __FILE__; // D:\server\www\file.php
__DIR__ - The directory of the current php file. If used inside an include, the directory of the included file is returned. This is equivalent to: dirname(__FILE__). Not have a trailing slash unless it is the root directory.
echo __DIR__; // D:\server\www
__FUNCTION__ - The function name in which this constant is accessed.
function someName() {
  echo __FUNCTION__;
someName();      // someName
__CLASS__ - Returns the class name as it was declared (case-sensitive).
class someClass {
  public function className() {
    return __CLASS__;

$obj = new someClass();
echo $obj->className();      // someClass
__METHOD__ - Returns the class method name as it was declared, including the class name (case-sensitive).
class someClass {
  public function someMethod() {
    return __METHOD__;

$obj = new someClass();
echo $obj->someMethod();      // someClass::someMethod

Daily Test with Code Example

Which HTML5 tag can be used to embed an external application (SWF, PDF) in web page?
<mark> <embed> <canvas>
<embed src="flash_game.swf" width="450" height="350" />
Which CSS pseudo-element adds a special style to the first line of a text?
:first-letter :before :first-line
#id:first-line {
  font-weight: bold;
  color: blue;
Click on the window object property which gets or sets the URL of current page.
window.location window.self window.status
var url = window.location;
Indicate the PHP function used to get the contents of a file or page and store it into a string.
fopen() file_put_contents() file_get_contents()
$homepage = file_get_contents("");
echo $homepage;
PHP Predefined Constants

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