Questions in: Core PHP

To delete a file by using PHP is very easy. Deleting a file means completely erase a file from a directory so that the file is no longer exist. PHP has an unlink() function that allows to delete a file. The PHP unlink() function takes two parameters $filename and $context.
<strong>
Syntax:</strong>

unlink( $filename, $context );

The htmlentities() function converts characters to HTML entities.

In PHP , both are variables. But $var is a variable with a fixed name. $$var is a variable who’s name is stored in $var. For example, if $var contains “user”, $$var is the same as $user.

<p>mysql_connect() and mysql_pconnect() both are working for database connection but with little difference. In mysql_pconnect(), ‘p’ stands for persistance connection.</p>
<p>When we are using mysql_connect() function, every time it is opening and closing the database connection, depending on the request .</p>
<p>But in case of mysql_pconnect() function,<br />
First, when connecting, the function would try to find a (persistent) connection that’s already open with the same host, username and password. If one is found, an identifier for it will be returned instead of opening a new connection.<br />
Second, the connection to the SQL server will not be closed when the execution of the script ends. Instead, the connection will remain open for future use (mysql_close() will not close connection established by mysql_pconnect()).</p>
<p>mysql_pconncet() is useful when you have a lot of traffice on your site. At that time for every request it will not open a connection but will take it from the pool. This will increase the efficiency of your site. But for general use mysql_connect() is best.</p>
<p>mysql_pconnect() is deprecated as of PHP 5.5.0, and will be removed in the future because it has several disadvantage.</p>

<p>You can simply use the PHP date() function to get the current data and time in various format, for example, date('d-m-y h:i:s'), date('d/m/y H:i:s'), and so on.</p>

<p>enctype(ENCode TYPE) attribute specifies how the form-data should be encoded when submitting it to the server. multipart/form-data is one of the value of enctype attribute, which is used in form element that have a file upload. multi-part means form data divides into multiple parts and send to server.</p>

<p>The action attribute of the FORM tag provides the URL of the program (which is in the server) that receives the information from the form and processes it.</p>