Question:

(a) A website wishes to use sessions to store the user's name and display a welcome message on all its pages. The user enters his username in a textbox called "username".

(i) Write the PHP script to create the session and store the user's name in that session.

(ii) Write the PHP script to output the session contents to the user only if the session exists and it is not empty.

(b) Write the PHP script that allows you to:

(i) Create a file named "logfile.log" in the same folder.

(ii) Insert the text "Monday 12 Oct" in this file.

(c) A website wishes to store user complaints in a database. The user enters his comments in a textarea called "complaints" and the form uses the POST method.

Write the PHP script to retrieve and clean up the user input before it can be safely stored in the database and explain your code.

(d) Outline the md5() function and provide an example of a situation where it is necessary to use the md5() function.