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PHP Interview Questions and Answers for 1 Year Experienced

• Posted by PHP Gurukul May 1, 2023 Filed in Business #010-111 Questions and Answers  5 views
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  1. What is PHP, and what does it stand for?
  PHP is a server-side scripting language used for web development. It stands for Hypertext Preprocessor.

  2. What is the current stable version of PHP?
  The current stable version of PHP is PHP 8.1.0.

  3. What is the difference between include and require?

  include and require are both PHP language constructs used for including code from other files into your PHP script. The main difference between the two is the behavior when the file being included cannot be found or loaded.

  include includes the specified file and generates a warning message if the file cannot be found or loaded. This means that the PHP script will continue to execute even if the file being included is missing or contains errors. In other words, include is non-fatal.

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  For example:

   

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  <?php

  // include file.php

  include 'file.php';

   

  // rest of the code

  ?>

  require, on the other hand, also includes the specified file but generates a fatal error if the file cannot be found or loaded. This means that the PHP script will stop executing immediately if the file being included is missing or contains errors. In other words, require is fatal.

  For example:

   

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  <?php

  // require file.php

  require 'file.php';

   

  // rest of the code

  ?>

  In general, it is recommended to use require when including critical files that your code depends on, such as configuration files or library files, since it ensures that the script will not continue executing if the file is missing or contains errors. Use include for non-critical files or optional components.

  4. What is the difference between GET and POST methods?

  GET and POST are two HTTP methods used to send data between a client (such as a web browser) and a server. Here are the differences between them:

  1. Purpose: The GET method is used to request data from a server, while the POST method is used to submit data to be processed by a server.
  2. Data transfer: GET sends data as part of the URL, while POST sends data in the body of the request. This means that GET requests can be bookmarked and shared, while POST requests cannot.
  3. Security: Since GET sends data in the URL, it is less secure than POST, which sends data in the request body. This means that sensitive information such as passwords and credit card numbers should never be sent via GET.
  4. Caching: GET requests can be cached by the browser, while POST requests are not. This means that GET requests can be faster if the same data is requested multiple times, while POST requests are better for submitting data that should not be cached.

  In summary, the main difference between GET and POST is their purpose and how they send data. GET is used to request data, sends data as part of the URL, and can be cached by the browser. POST is used to submit data, sends data in the request body, and is more secure than GET.

  5. What is the difference between echo and print statements?

  In PHP, both echo and print statements are used to output strings or values to the browser or client. However, there are some differences between them:

  1. Return Value: print returns a value of 1, whereas echo does not return anything. This means that print can be used as part of a larger expression, while echo cannot.
  2. Syntax: echo does not need parentheses, while print requires them. For example, echo "Hello World"; is a valid statement, while print("Hello World"); is required for the print statement to work.
  3. Speed: echo is generally faster than print. This is because echo is a language construct, while print is a function. Language constructs are generally faster than functions in PHP.
  4. Usage: echo is used more often than print in PHP code, as it is more concise and faster.

  In summary, the main difference between echo and print statements in PHP is their syntax and return value. echo is faster and more commonly used, while print returns a value and requires parentheses.

  6. What is the use of htmlentities() function in PHP?

  The htmlentities() function converts characters to their corresponding HTML entities. This is useful when outputting user-generated content to prevent cross-site scripting (XSS) attacks.

  7. What is the difference between $_GET and $_POST?

  $_GET is an array containing data sent via the GET method, while $_POST is an array containing data sent via the POST method.

  8. What is the difference between public, private, and protected access modifiers in PHP?

  Public access modifiers allow a property or method to be accessed from anywhere, private access modifiers allow a property or method to be accessed only within the class, and protected access modifiers allow a property or method to be accessed within the class and any subclass.

  9. What is the difference between sessions and cookies in PHP?

  In PHP, both sessions and cookies can be used to store data on the client-side and pass data between pages on a website. However, there are some differences between them:

  1. Storage Location: Cookies are stored on the client-side, usually in the browser, while sessions are stored on the server-side. This means that cookies can be accessed and modified by the client, while sessions are only accessible by the server.
  2. Data Storage: Cookies can store small amounts of data, usually up to 4KB, while sessions can store larger amounts of data, limited only by the server’s resources.
  3. Persistence: Cookies can be persistent or non-persistent. Persistent cookies are stored on the client-side for a specific period of time, while non-persistent cookies are deleted when the browser is closed. Sessions, on the other hand, are non-persistent and are deleted when the user closes the browser or when the session expires.
  4. Security: Sessions are generally considered more secure than cookies, as the data stored in a session is only accessible on the server-side. Cookies can be intercepted and modified by malicious users, making them less secure.
  5. Implementation: Cookies are implemented using the setcookie() function, while sessions are implemented using the session_start() function.

  In summary, the main differences between sessions and cookies in PHP are their storage location, data storage, persistence, security, and implementation. Sessions are more secure and can store larger amounts of data, while cookies are more flexible and can be used for persistent data storage.

  10. How do you connect to a MySQL database using PHP?

  You can connect to a MySQL database using the mysqli_connect() or PDO class in PHP.

  11. What is the difference between mysqli and PDO?

  Mysqli is a PHP extension used for accessing MySQL databases, while PDO is a PHP extension used for accessing multiple databases, including MySQL, Oracle, and PostgreSQL.

  12. What is the use of the isset() function in PHP?
  The isset() function is used to determine if a variable is set and is not NULL.

  13.What is the difference between strpos() and strstr() functions in PHP?

  In PHP, strpos() and strstr() are two different functions used to find a substring within a string. Here are some differences between them:

  1. Return Value: strpos() returns the numeric position of the first occurrence of a substring within a string, or false if the substring is not found. strstr(), on the other hand, returns the part of the string from the first occurrence of the substring to the end of the string, or false if the substring is not found.
  2. Parameters: strpos() takes two parameters – the string to search and the substring to find. strstr() takes two parameters – the string to search and the substring to find – and an optional third parameter that can be used to return everything before the first occurrence of the substring.
  3. Case Sensitivity: By default, both strpos() and strstr() are case-sensitive. However, strpos() has an optional third parameter that can be used to make the search case-insensitive.
  4. Performance: strpos() is generally faster than strstr(), as it only needs to return a numeric position, while strstr() needs to return a substring.

  In summary, the main differences between strpos() and strstr() in PHP are their return value, parameters, case sensitivity, and performance. strpos() returns the numeric position of a substring, while strstr() returns the substring itself. strpos() is faster, while strstr() has an optional parameter to return everything before the substring.

   

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