Question:How does security can be provided in CodeIgniter? 

CodeIginter provides a number of security options to handle to our applications:
a. URL security
b, Global security
c. Filtering data
d. Password salting
e. Database security
f. Cross-site scripting

Question:Write the functions of Email class. 

There is a number of email class functions available in CodeIginter:
$this->email->from()
$this->email->reply_to()
$this->email->to() 
$this->email->cc() 
$this->email->bcc()
$this->email->subject()
$this->email->message() 
$this->email->set_alt_message() 
$this->email->clear() 
$this->email->send() 
$this->email->attach() 
$this->email->print_debugger()

Question:What is a library? 

A CodeIgniter library is simply a class file that abstracts functionality into easy-to-use functions tha take much of the strain off the developer. The term "class" and "library" are used interchangeably in CodeIgniter.

Question:What is stored in a session when you use session class? 

A codeIgniter session is simply an array containing the following data:

1. The user's unique Session ID
2. The use's IP address
3. The user's User Agent string
4. The "Last activity" timestamp

Question:Define the term "Session ID". 

Session ID: This is a randomly-generated number, which is hashed with MD5 for portability, and is regenerated every five minutes.

Question:What is the purpose of Flash data? 

CodeIgniter supports flashdata - data that is only available for one server request, and then removed. Flash data is very useful, and is usually used for informational messages such as "You hava been logged out" or "Removed user account". Flash variable are prefixed with flash_.

Question:What are the functions of num_rows() and num_fields()? 

num_rows() function will return the total number of rows returned from a query.
num_fields() function will return the number of fields returned by the query.

Question:What is the purpose of active record caching? 

It enables us to save a query for use later on in our script execution. Usually, an SQL query is reset after it has been completed. With Active Record cashing we can prevent this reset and reuse queries easily.