Jnr PHP/Codeigniter Developer Interview Preparation Guide

In CodeIgniter, helpers are group of function in a particular category that assist you to perform specific functions. In CodeIgniter, you will find many helpers like URL helpers- helping in creating links, Text helpers- perform various text formatting routines, Cookies- helpers set and read cookies. You can load helper file by using command $this->load->helper (‘name’) ;

For CodeIgniter, inhibitor is an error handler class, using the native PHP functions like set_exception_handler, set_error_handler, register_shutdown_function to handle parse errors, exceptions, and fatal errors.

You can activate CSRF (Cross Site Request Forgery) protection in CodeIgniter by operating your application/config/config.php file and setting it to

$config [ ‘csrf_protection’] = TRUE;

If you avail the form helper, the form_open() function will insert a hidden csrf field in your forms automatically

Check if “display_errors” is equal “on” in the php.ini or declare “ini_set('display_errors', 1)” in your script.
Then, include “error_reporting(E_ALL)” in your code to display all types of error messages during the script execution.

Enabling error messages is very important especially during the debugging process as one can instantly get the exact line that is producing the error and can see also if the script in general is behaving correctly.

If hello is true, then the function must print hello, but if the function doesn’t receive hello or hello is false the function must print bye.

<?php
function showMessage($hello=false){
echo ($hello)?'hello':'bye';
}
?>

SQL injections are a method to alter a query in a SQL statement send to the database server. That modified query then might leak information like username/password combinations and can help the intruder to further compromise the server.

To prevent SQL injections, one should always check & escape all user input. In PHP, this is easily forgotten due to the easy access to $_GET & $_POST, and is often forgotten by inexperienced developers. But there are also many other ways that users can manipulate variables used in a SQL query through cookies or even uploaded files (filenames). The only real protection is to use prepared statements everywhere consistently.

Do not use any of the mysql_* functions which have been deprecated since PHP 5.5 ,but rather use PDO, as it allows you to use other servers than MySQL out of the box. mysqli_* are still an option, but there is no real reason nowadays not to use PDO, ODBC or DBA to get real abstraction. Ideally you want to use Doctrine or Propel to get rid of writing SQL queries all together and use object-relational mapping which binds rows from the database to objects in the application.

Just simply by parent::constructor() in an inherited class constructor.

Cookies will only persist for the time you define. To do it for 1 year you can simply do:

setcookie( "cookieName", 'cookieValue', strtotime( '+1 year' ) ); //set for 1 year

This is a tricky question. To understand it, you need to understand how objects are instantiated.

Explain the starship operator and why it returns the given output

echo 1.5 <=> 2.5; // -1
echo "a" <=> "a"; // 0
echo [1, 2, 3] <=> [1, 2, 4]; // -1