Answer:- PHP session_start() function is used to start the session. It starts new or resumes the current session. It returns the current session if the session is created already. If the session is not available, it creates and returns new sessions.

Answer:- The main difference between session and cookie is that cookies are stored on users computer in the text file format while sessions are stored on the server side. Cookies cant hold multiple variables, on the other hand, Session can hold multiple variables. You can manually set an expiry for a cookie, while session only remains active as long as browser is open.

Answer:- PHP fopen() function is used to open file or URL and returns resource. It accepts two arguments: $filename and $mode Syntax: resource fopen ( string $filename , string $mode [, bool $use_include_path = false [, resource $context ]] )

Answer:- PHP provides various functions to read data from the file. Different functions allow you to read all file data, read data line by line, and read data character by character. PHP file read functions are given below: fread(), fgets(), fgetc()

Answer:- PHP fwrite() and fputs() functions are used to write data into file. To write data into a file, you need to use w, r+, w+, x, x+, c or c+ mode.

Answer:- The unlink() function is used to delete a file in PHP. bool unlink (string $filename)

Answer:- You should just run the PHP command line interface (CLI) and specify the file name of the script to be executed as follows.

Answer:- The move_uploaded_file() function is used to upload file in PHP. bool move_uploaded_file ( string $filename , string $destination )

Answer:- How to download file in PHP?

Answer:- The mail() function is used to send email in PHP. bool mail($to,$subject,$message,$header);

Answer:- There are two methods to connect MySQL database with PHP. Procedural and object-oriented style.

Answer:- The mysqli_connect() function is used to create a connection in PHP. resource mysqli_connect (server, username, password)

Answer:- Since PHP 4.3, mysql_reate_db() is deprecated. Now you can use the following 2 alternatives. mysqli_query() , PDO::_query()

Answer:- By default, the maximum execution time for PHP scripts is set to 30 seconds. If a script takes more than 30 seconds, PHP stops the script and returns an error. You can change the script run time by changing the max_execution_time directive in the php.ini file. When a script is called, set_time_limit function restarts the timeout counter from zero. It means, if default timer is set to 30 sec, and 20 sec is specified in function set_time_limit(), then script will run for 45 seconds. If 0sec is specified in this function, script takes unlimited time.