php interview questions

# 27 basics questions for php Interview

1) What is PHP?
PHP is a web language based on scripts that allow developers to dynamically create generated web pages.

2) What do the initials of PHP stand for?
PHP means PHP: Hypertext Preprocessor.

3) Which programming language does PHP resemble?
PHP syntax resembles Perl and C

4) What does PEAR stand for?
PEAR means PHP Extension and Application Repository. It extends PHP and provides a higher level of programming for web developers.

5) What is the actually used PHP version?
Version 7.1 or 7.2 is the recommended version of PHP.

6) How do you execute a PHP script from the command line?
Just use the PHP command line interface (CLI) and specify the file name of the script to be executed as follows:
php script.php

7) How to run the interactive PHP shell from the command line interface?
Just use the PHP CLI program with the option -a as follows:
php -a

8) What is the correct and the most two common way to start and finish a PHP block of code?
The two most common ways to start and finish a PHP script are:
 <?php [   ---  PHP code---- ] ?> and <? [---  PHP code  ---] ?>

9) How can we display the output directly to the browser?
To be able to display the output directly to the browser, we have to use the special tags <?= and ?>.

10) What is the main difference between PHP 4 and PHP 5?
PHP 5 presents many additional OOP (Object Oriented Programming) features.

11) Is multiple inheritance supported in PHP?
PHP supports only single inheritance; it means that a class can be extended from only one single class using the keyword extended.

12) What is the meaning of a final class and a final method?
final is introduced in PHP5. Final class means that this class cannot be extended and a final method cannot be overridden.

13) How is the comparison of objects done in PHP?
We use the operator == to test is two objects are instanced from the same class and have same attributes and equal values. We can test if two objects are referring to the same instance of the same class by the use of the identity operator ===.

14) How can PHP and HTML interact?
It is possible to generate HTML through PHP scripts, and it is possible to pass pieces of information from HTML to PHP.

15) What type of operation is needed when passing values through a form or an URL?
If we would like to pass values through a form or an URL, then we need to encode and to decode them using htmlspecialchars() and urlencode().

16) How can PHP and Javascript interact?
PHP and Javascript cannot directly interact since PHP is a server side language and Javascript is a client-side language. However, we can exchange variables since PHP can generate Javascript code to be executed by the browser and it is possible to pass specific variables back to PHP via the URL.

17) What is needed to be able to use image function?
GD library is needed to execute image functions.

18) What is the use of the function imagetypes()?
imagetypes() gives the image format and types supported by the current version of GD-PHP.

19) What are the functions to be used to get the imags properties (size, width, and height)?
The functions are getimagesize() for size, imagesx() for width and imagesy() for height.

20) How failures in execution are handled with include() and require() functions?
If the function require() cannot access the file then it ends with a fatal error. However, the include() function gives a warning, and the PHP script continues to execute.

21) What is the main difference between require() and require_once()?
require(), and require_once() perform the same task except that the second function checks if the PHP script is already included or not before executing it.
(same for include_once() and include())

22) How can I display text with a PHP script?
Two methods are possible:
<!--?php echo Method 1; print Method 2; ?-->

23) How can we display information of a variable and readable by a human with PHP?
To be able to display a human-readable result we use print_r().

24) How is it possible to set an infinite execution time for PHP script?
The set_time_limit(0) added at the beginning of a script sets to infinite the time of execution to not have the PHP error maximum execution time exceeded. It is also possible to specify this in the php.ini file.

25) What does the PHP error Parse error in PHP - unexpected T_variable at line x means?
This is a PHP syntax error expressing that a mistake at the line x stops parsing and executing the program.

26) What should we do to be able to export data into an Excel file?
The most common and used way is to get data into a format supported by Excel. For example, it is possible to write a .csv file, to choose for example comma as a separator between fields and then to open the file with Excel.

27) What is the function file_get_contents() useful for?
file_get_contents() lets reading a file and storing it in a string variable.