21 PHP Interview Questions & Answers You Should Prepare In 2021
Are you preparing for the PHP developer position? Here are some of the most asked questions in a PHP interview.
If you're starting in WordPress development, PHP is a great place to start. It is an elementary and straightforward language, making it an excellent programming language for beginners. It is relatively easy to learn, and it is crucial to the development of online applications.
To learn PHP, you can use dozens of free PHP tutorials. Whatever your learning style, you'll find a course that's right for you. Now let's move on to the questions asked in a PHP interview.
1) What is PHP?
PHP is a general-based scripting language particularly suited to web development. Danish-Canadian programmer Rasmus Lerdorf created it in 1994.
2) What does PHP stand for?
PHP stands for "Hypertext Preprocessor."
3) What is the full form of PEAR?
It stands for "PHP Extension and Application Repository." It is an extension of PHP that provides web developers with more programming capabilities.
4) How do you execute a PHP script from the command line?
You can execute PHP scripts using the command line by using the PHP command-line interface (CLI) and specifying the file name of the script that you want to execute like:
php script.php
5) How to run the interactive PHP shell from the command line interface?
PHP CLI program can be used with the -a option as follows:
php -a
6) Does PHP support multiple inheritance?
No, PHP supports only a single inheritance meaning that a class can be extended from only one solo class using the keyword 'extended.
7) How does PHP compare objects?
Using the operator '==,' we can test if two objects are mainly from the same class and have similar attributes and equal values. Meanwhile, the identity operator '===' can be used to determine if two objects refer to the same instance of the same class.
8) How can Javascript and PHP interact?
Objectively, PHP and Javascript cannot directly interact since PHP is a server-side language and Javascript is a client-side language. Nonetheless, we can exchange variables since PHP can generate Javascript code to be executed by the browser. So, it is attainable to pass specific variables back to PHP via the URL.
9) How can I display text via a PHP script?
There are two possible ways to display text with a PHP script:
<!--?php echo "Way 1";
print "Way 2"; ?-->
10) Are there ways to set an endless execution time for PHP scripts, and how do they work?
Yes, we can set an endless execution time for PHP scripts. They work as follows: The set_time_limit(0) function added to the beginning of a script prevents the PHP error 'maximum execution time exceeded' from occurring. This option is also available in the php.ini file.
11) How can a PHP script connect to a MySQL database?
With mysqli_connect(), you can connect to a MySQL database as follows:
<!--?php $database = mysqli_connect("HOST", "USER_NAME", "PASSWORD"); mysqli_select_db($database,"DATABASE_NAME"); ?-->
12) Explain the use of the function mysql_pconnect()?
Mysql_pconnect() maintains a persistent connection to the database, so the connection does not close when the PHP script ends. PHP 7.0 and above do not support this function.
13) What does the unlink() function do?
File system handling is handled by the unlink() function. As for its work, it simply removes the file provided as an entry.
14) What does the unset() function do?
Unset() function makes a variable undefined. It is primarily used to manage variables.
15) What is the most appropriate hashing method to hash passwords?
In most cases, it is recommended to use the natively supported hashing algorithms such as crypt() or hash() rather than the standard hashing algorithms such as md5, sha1, or sha256 since they are designed to be fast. Thus, hashing passwords with these algorithms can create vulnerabilities.
16) How is it possible to cast types in PHP?
Before the variable to be cast, the output type must be specified in parentheses as follows:
- (int), (integer) - cast to integer
- (bool), (boolean) - cast to boolean
- (float), (double), (real) - cast to float
- (string) - cast to string
- (array) - cast to array
- (object) - cast to object
17) How does the ternary conditional operator work in PHP?
It consists of three expressions, a condition and two operands describing what to do if the condition is true or false, as follows:
- Expression_1?Expression_2 : Expression_3;
18) What is the use of function func_num_args()?
The Function func_num_args() returns the number of parameters passed into a function.
19) What's the difference between sleep and wakeup?
_sleep - returns the array of variables that need to be saved.
_wakeup - retrieves those variables.
20) Is it possible to share a single instance of Memcache across multiple PHP projects?
Yes, it is possible to share a single instance of Memcache between multiple projects. Memcache is a storage area in memory and can be deployed on one or more servers. In addition, you can configure your client to talk to particular instances. Thus, two Memcache processes can be running on the same host, and they will still be independent. But, if you have partitioned your data, you need to know which instance to retrieve data from or put into.
21. What are some of the best frameworks for PHP?
It isn't easy to get a definitive list of PHP frameworks. Wikipedia list contains around 40 PHP Frameworks, but some are better known as content management systems, and indeed there are several more.
These are some of the most popular PHP frameworks:
- Laravel
- Symfony
- CodeIgniter
- Zend Framework / Laminas Project
- Yii (Framework)
- CakePHP
- Slim
- Phalcon
- FuelPHP
- Fat-Free Framework
If you have made it this far, then certainly you are willing to learn more. Here are some more topics related to interviewing questions that we think will be interesting for you.