PHP’s configuration file is called php.ini.

Array                                              Descriptions
--------------------------------           -----------------------------------
$_FILES['userfile']['name']              The original name of the file on the client machine.

$_FILES['userfile']['type']                The MIME type of the file if the browser provided 

                                                   this information. An example would be "image/gif".

$_FILES['userfile']['size']                The size, in bytes, of the uploaded file.

$_FILES['userfile']['tmp_name']      The temporary filename of the file in which the

                                                  uploaded file was stored on the server.

$_FILES['userfile']['error']              The error code  associated with this file upload.

move_uploaded_file( string filename, string destination)

mysql_fetch_array:
Fetch a result row as an associative array and a numeric array.

mysql_fetch_object:
Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows.

mysql_fetch_row():
Fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.

strstr() returns part of a given string from the first occurrence of a given substring to the end of the string.
For example:
strstr("user@example.com","@") will return "@example.com".

stristr() is idential to strstr() except that it is case insensitive.

We can use the preg_match() function with “/.*@(.*)$/” as the regular expression pattern.
For example:
preg_match("/.*@(.*)$/","https://info@abc.com",$data);
echo $data[1];
?>

include()
The include() function takes all the content in a specified file and includes it in the current file. If an error occurs, the include() function generates a warning, but the script will continue execution.

include_once()
File will not be included more than once. If we want to include a file once only and further calling of the file will be ignored then we have to use the PHP function include_once().

require()
The require() function is identical to include(), except that it handles errors differently. The require() generates a fatal error, and the script will stop.

require_once()
The required file is called only once when a page is open and further calling of the file will be ignored.

<?php
session_start();
// store session data
$_SESSION['views']=1;
unset($_SESSION['views']); // If you wish to delete some session data, you can use the unset()
session_destroy(); // You can also completely destroy the session by calling the session_destroy() function. session_destroy() will reset your session and you will lose all your stored session data.
?>