What are advanced PHP interview questions and answers?
PHP is a widely-used open source programming language suitable for building dynamic websites and mobile APIs.
Despite its long history, the demand for PHP has not waned over the years. According to the US Board of Labor Statistics, there will be a 15% increase in web development positions, including PHP positions, by 2026.
In this blog post, we’ve compiled a comprehensive list of common PHP interview questions frequently encountered in interviews and the best ways to answer them.
This list of advanced PHP interview questions will help you prepare for your interview, boost your confidence, and increase your chances of landing that Backend Developer job of your dreams!
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10 Advanced PHP Interview Questions and Answers
1. What is the use of sessions in PHP?
A session is a global variable stored on the server. Each session is assigned a unique ID to retrieve stored values. Sessions have the capacity to store relatively large data compared to cookies.
Session values are automatically deleted when the browser is closed. However, this problem is solved by storing user information (e.g., username, favorite color, etc.) to be used on multiple pages. By default, session variables persist until the user closes the browser.
Session variables hold information about a single user and are available on all pages in a single application.
2. What is overloading and overriding in PHP?
Function overloading and overriding are features of OOPs in PHP.
In function overloading, multiple functions can have the same method signature but a different number of arguments. However, if the function is overridden, multiple functions will have the same method signature and number of arguments.
Function overloading contains the same function name, and this function performs different tasks based on the number of arguments.
PHP function overloading is done with the help of the magic function __call(). This function takes the function name and arguments.
3. How can you create a database using PHP and MySQL?
A database is a tool that helps to efficiently retrieve, insert and delete data from the database and organizes data into tables, views, schemas, reports, etc.
The steps to create a MySQL database using PHP are as follows:
- Establish a connection from your PHP script to the MySQL server
- If the connection is successful, write a SQL query to create a database and store it in a string variable
- Execute the query.
4. Is multiple inheritance supported in PHP?
PHP doesn’t support multiple inheritance but can be implemented in PHP using Interfaces or PHP using Properties instead of classes.
Attributes (Using Classes with Traits): Attribute is a type of class that enables multiple inheritance.
Classes, case classes, objects, and properties can’t all extend more than one class, but can extend multiple properties at once.
5. How to display text with a PHP script?
PHP allows you to display text in various formats using various built-in methods.
You can use the echo command to display text, including numeric, strings, and arrays.
There are two ways to do this:
<!–?php echo “Method 1”; print “Method 2”; ?–>
6. How do you execute a PHP script from the command line?
PHP Installation for Windows Users:
- Step 1: First, you can start by downloading PHP from the official website.
- Step 2: Extract the downloaded .zip file to your preferred location.
- Step 3: Now, you need to add the folder C:php to the Environment Variable Path so that it can be accessed from the command line. To do this, you must right-click on the My Computer or This PC icon and select Properties from the context menu. Then click the Advanced system settings link, then click Environment Variables. In the System Variables section, you must find the PATH environment variable and then select it and edit it. If there is no PATH environment variable, you need to click on New. In the Edit System Variable (or New System Variable) window, you must specify the value of the PATH environment variable (C:php or the location of our extracted PHP files). After that, you have to click OK and close all remaining windows by clicking OK.
PHP Installation for Linux Users:
Linux users can install PHP using the following command.
apt-get install php5-common libapache2-mod-php5 php5-cli
It will install PHP with an apache server. For more information, click here.
7. What is the main difference between require() and require_once()?
| require() | require_once() |
|---|---|
| The require() function is used to include a PHP file into another, irrespective of whether the file is included before or not. | The require_once() will first check whether a file is already included or not, and if it’s already included, it won’t include it again. |
| This function is mostly used where you want to include a certain code again and again. | This function is mostly used where you want to include a certain code just once. |
| Use require() to load template-like files. | Use require_once() to load dependencies (classes, functions, constants). |
| The require() function will execute every time it’s called. | The require_once() function won’t execute every time it’s called (It won’t execute, if the file to be included is included before). |
References: GeeksforGeek
8. What are the PHP Magic Methods?
All functions starting with __ names are magic methods in PHP
and they aim to perform specific tasks.
PHP offers several ‘magic’ methods that allow you to do some nice tricks in object-oriented programming.
All these function names are reserved and can’t be used for other than associated magic functions. The magical method in a class must be declared as public. These methods act as interceptors that are called automatically when certain conditions are met.
Here is the list of Magic Functions available in PHP:
9. How to encrypt password in PHP?
PHP provides a number of different encryption methods. PHP has a hash algorithm to encrypt the password. The most used functions for password encryption are md5(), crypt(), and password_hash().
The crypt() function is used to create one-way encryption. Takes an input string and an optional parameter. PHP uses DES for encryption.
10. What is the difference between runtime exception and compile time exception?
An error or exception refers to the interruption of code execution due to a failure to achieve the expected result for the end-user.
An exception that occurs at compile time is called a checked exception. On the other hand, an exception that occurs at runtime is called an unchecked exception.
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