PHP Interview Questions and Answers

1. What is PHP?
   PHP is a server side scripting language commonly used for web applications. PHP has many frameworks and cms for creating websites.Even a non technical person can cretae sites using its CMS.WordPress,osCommerce are the famus CMS of php.It is also an object oriented programming language like java,C-sharp etc.It is very eazy for learning
2. What is the use of "echo" in php?
   It is used to print a data in the webpage, Example: <?php echo 'Car insurance'; ?> , The following code print the text in the webpage
3. How to include a file to a php page?
   We can include a file using "include() " or "require()" function with file path as its parameter.
4. What's the difference between include and require?
   If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.
5. require_once(), require(), include().What is difference between them?
   require() includes and evaluates a specific file, while require_once() does that only if it has not been included before (on the same page). So, require_once() is recommended to use when you want to include a file where you have a lot of functions for example. This way you make sure you don't include the file more times and you will not get the "function re-declared" error.
6. Differences between GET and POST methods ?
   We can send 1024 bytes using GET method but POST method can transfer large amount of data and POST is the secure method than GET method .
7. How to declare an array in php?
   Eg : var $arr = array('apple', 'grape', 'lemon');
8. What is the use of 'print' in php?
   This is not actually a real function, It is a language construct. So you can use with out parentheses with its argument list.
   Example print('PHP Interview questions'); 
   print 'Job Interview ');
9. What is use of in_array() function in php ?
   in_array used to checks if a value exists in an array
10. What is use of count() function in php ?
    count() is used to count all elements in an array, or something in an object
11. What's the difference between include and require?
    It's how they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.
12. What is the difference between Session and Cookie?
    The main difference between sessions and cookies is that sessions are stored on the server, and cookies are stored on the user's computers in the text file format. Cookies can't hold multiple variable while session can hold multiple variables..We can set expiry for a cookie,The session only remains active as long as the browser is open.Users do not have access to the data you stored in Session,Since it is stored in the server.Session is mainly used for login/logout purpose while cookies using for user activity tracking
13. How to set cookies in PHP?
    Setcookie("sample", "ram", time()+3600);
14. How to Retrieve a Cookie Value?
    eg : echo $_COOKIE["user"];
15. How to create a session? How to set a value in session ? How to Remove data from a session?
    Create session : session_start();
    Set value into session : $_SESSION['USER_ID']=1;
    Remove data from a session : unset($_SESSION['USER_ID'];
16. what types of loops exist in php?
    for,while,do while and foreach (NB: You should learn its usage)
17. How to strip whitespace (or other characters) from the beginning and end of a string ?
18. The trim() function removes whitespaces or other predefined characters from both sides of a string.
19. What is the use of header() function in php ?
    The header() function sends a raw HTTP header to a client browser.Remember that this function must be called before sending the actual out put.For example, You do not print any HTML element before using this function.
20. How to redirect a page in php?
    The following code can be used for it, header("Location:index.php");
21. How stop the execution of a php scrip ?
    exit() function is used to stop the execution of a page
22. How to set a page as a home page in a php based site ?
    index.php is the default name of the home page in php based sites
23. How to find the length of a string?
    strlen() function used to find the length of a string
24. what is the use of rand() in php?
    It is used to generate random numbers.If called without the arguments it returns a pseudo-random integer between 0 and getrandmax(). If you want a random number between 6 and 12 (inclusive), for example, use rand(6, 12).This function does not generate cryptographically safe values, and should not be used for cryptographic uses. If you want a cryptographically secure value, consider using openssl_random_pseudo_bytes() instead.
25. what is the use of isset() in php?
    This function is used to determine if a variable is set and is not NULL
26. What is the difference between mysql_fetch_array() and mysql_fetch_assoc() ?
    mysql_fetch_assoc function Fetch a result row as an associative array, While mysql_fetch_array()fetches an associative array, a numeric array, or both
27. What is mean by an associative array?
    Associative arrays are arrays that use string keys is called associative arrays.
28. What is the importance of "method" attribute in a html form?
    "method" attribute determines how to send the form-data into the server.There are two methods, get and post. The default method is get.This sends the form information by appending it on the URL.Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
29. What is the importance of "action" attribute in a html form?
    The action attribute determines where to send the form-data in the form submission.
30. What is the use of "enctype" attribute in a html form?
    The enctype attribute determines how the form-data should be encoded when submitting it to the server. We need to set enctype as "multipart/form-data" when we are using a form for uploading files

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About Mariano

I'm Ethan Mariano a software engineer by profession and reader/writter by passion.I have good understanding and knowledge of AngularJS, Database, javascript, web development, digital marketing and exploring other technologies related to Software development.