Friday, March 25, 2011

PHP Interview Question Part 4

1. Describe about the security vulnerability of PHP?
According to the information obtained from the National vulnerability database, PHP has more than quarter of the software vulnerabilities discovered in 2008. Out of 33.33% software and scripts vulnerability PHP amounts to almost quarter of them. Register_globals a feature present in PHP is responsible for most of these vulnerabilities and now it is deprecated by PHP. Most of these security vulnerabilities occur due to poor programming techniques.
 
2. Explain about the data types in PHP?
PHP stores information numerical in a platform dependent range. Unsigned integers can be easily converted to signed integers. Decimal, octal, and hexadecimal notations can be easily assigned to integers. Floating point notation and two forms of scientific notation can be easily assigned to Real numbers. Zero is considered as false and all non zero numbers are considered as true.

3. What is a PHP accelerator?
PHP accelerator increases the speed of applications written in PHP. This boost of performance can be around 2-10 times. PHP accelerator increases the speed of the applications by decreasing parsing each and every time a PHP application runs. It depends upon factors such as time taken for execution of the PHP script and the actual percentage of the source code requested.
 
4. Explain about PHP cookies?
A Cookie is placed on the user desktop which uniquely identifies the user and every time a user views the webpage the same cookie is retrieved. With PHP a programmer can create and retrieve information simultaneously. The setcookie() function is used to create a cookie and PHP $_COOKIE variable helps the programmer to retrieve the cookie stored on the users computer. These both functions can function simultaneously.

5. Explain about Functions in PHP?
PHP has a large pool of functions and a huge number of them can be created by extensions. These functions can be defined at runtime by defining them inside the code. These functions have to be defined inside the parenthesis except for a class constructor function where there is no argument. Functions can be called or referenced by specifying their name.
 
6. Explain about objects in PHP?
In previous versions of PHP, object was fully copied before assigning a variable to a method. This problem was solved in new versions of PHP by the handle function. Many of the features present in PHP 5 are adopted from C++. Some of the features which are incorporated are restricted classes such as private and public, abstract and final classes, abstract and final methods, constructors and destructors with exception handling borrowed from C++.

7. Describe about PHP error and logging information?
Error handling function allows the user to detect the error and do necessary changes which paved the way for the error.
Logging functions pave the way for users to use log applications and send messages to system logs, email or for other specific purpose.
PHP has efficient error and logging constants to its credit. Some of them are E_ERROR, E_NOTICE, E_ALL, E_STRICT, etc.
 
 

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