Showing posts with label php-interview-questions-answers. Show all posts
Showing posts with label php-interview-questions-answers. Show all posts

Top PHP Interview Questions with Answers For Job

  What is PHP?

    PHP is a server side scripting language  used for web development applications.
    Php is the powerful tool for making dynamic website.
    Many open source, free and commercial scripts    and   Stuff made by php

 What is a data type?

A Data type is the classification of data into a category according to its attributes;
• Alphanumericcharacters are classified as strings
• Whole numbersare classified integers
• Numberswith decimal pointsare classified as floating points.
• True or falsevalues are classified as Boolean.
PHP is a loosely typed language;it does not have explicit defined data types.

What is a variable?

A variable is a name given to a memory location that stores data at runtime.
 The scope of a variable determines its visibility.
A global variable is accessible to all the scripts in an
application. A local variable is only accessible to the script
that it was defined in.

How to retrieve a secure URL?
To retrieve secure URLs, the cURL extension needs access to an SSL library, such as OpenSSL.
$c = curl_init('');
curl_setopt($c, CURLOPT_RETURNTRANSFER, 1);
 $page = curl_exec($c); curl_close($c);

Why you should use variables?

Variables help separate data from the program algorithms. The same algorithm can be used
for different input data values. For example, suppose that you are developing a calculator
program that adds up two numbers, you can create two variables that accept the numbers
then you use the variables names in the expression that does the addition.

  How to show all PHP runtime errors?
   Add error_reporting function set  1 .

  What is htaccess?

   .htaccess files are configuration files of Apache Server which provide
   a way to make configuration changes on a per-directory basis.

How to redirect a user to a page?

The redirect URL must include the protocol and hostname.

   What is  echo in php?

    It is a keyword.
    It is used to print  data on the webpage, like that <?php echo 'test'; ?> ,
    How to include a file to a php page?

    Add include a file using include() or require() function with the path.

    What's the difference between include and require?

    PHP provides two constructs to load code and HTML from another module: require and include.
    They both load a file as the PHP script runs, work in conditionals and loops, and complain if
    the file being loaded can't be found. The main difference is that attempting to require a
   nonexistent file is a fatal error, while attempting to include such a file produces a warning
    but does not stop script execution.

    If the file is not found by require(), it will gives a fatal error and stop the execution of the script.
    If the file is not found by include(), it  will gives a warning , but execution will continue.

    will not get the "function re-declared" error.
    Differences between GET and POST methods ?
    A GET request encodes the form parameters in the URL, in what is called a query string:

    A POST request passes the form parameters in the body of the HTTP request, leaving the URL untouched.
    POST requests are not idempotent. This means that they cannot be cached,
    and the server is recontacted every time the page is displayed.

    How to declare an array php?

    Example : var $arr = array('ie', 'firefox', 'safari');

    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.

    What is  in_array() function?

    The in_array( ) function returns true or false, depending on whether the first
     argument is an element in the array given as the second argument.
    in_array used to checks if a value exists in an array that Searching for Values of array.
    What is count() function in php ?

    The count( ) and sizeof( ) functions are identical in use and effect.
    They return the number of elements in the array.

    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.

    What is the difference between Session and Cookie?

    sessions are stored on the server, and cookies are stored on the client’s computers in the text file format.
    A cookie is a bit of information that the server can give to a client.
    Every session has a data store associated with it. You can register variables to be loaded
    from the data store when each page starts and saved back to the data store when the page ends.

   How to set cookies in PHP?

    Setcookie("test", "sem", time()+3600);

    How to Retrieve a Cookie Value?
     echo $_COOKIE["test"];

    How to create a session? 

    Create session by  session_start();

   How to set a value in session ?

    Set value into session by  $_SESSION['test_ID']=1987654;

   How to Remove data from a session?

   Remove data from  session -> session_unset($_SESSION['test_ID'];

    How to create a mysql connection?
    call mysql_connect(servername,username,password);

    How to select a database?

    call mysql_select_db($db_name);

    How to execute an sql query? How to fetch its result ?
    $my_qry = mysql_query("SELECT * FROM `test` WHERE `test_id`='16'; ");
    $result = mysql_fetch_array($my_qry);
    echo $result['First_test_name'];

    How to get the resultset of MySQL using PHP?
        1. mysql_fetch_row
        2. mysql_fetch_array
        3. mysql_fetch_object
        4. mysql_fetch_assoc
    How to strip whitespace or other characters from the beginning and end of a string ?

    The trim() function removes whitespaces or other predefined characters from both sides of a string.
    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.
    How to redirect a page in php?

    The following code can be add for it, header("Location:test.php");
    How stop the execution of a php scrip ?

    exit() function  stop the execution of a page.
    How to get the length of a string?

    strlen() function  gives  the length of a string

    How to generate random numbers in php?

    Add rand function  to generate random numbers.

    How  to varify a variable in php?

    This is_set  function is used to determine if a variable is set and is not .   

    What is mean by an associative array?

    Associative arrays are arrays that indexed by string keys is called associative arrays.

    How do you define a constant?

    Using define() directive, like  that define ("MYCONSTANT",765754);
    How send email using php?

    To send email using PHP, you use the mail() function.This mail() function accepts 5 parameters

    How to find current date and time?

    The date() function gives  the current date and time .
    What is the use of ksort in php?

    Its  sort an array by key in reverse order.
  Who is the father of PHP ?

  Rasmus Lerdorf is known as the father of PHP.     
    How to delete a file from the system?

    Unlink() deletes the  file from the file system.
    How to get the value of current session id?

    session_id() function gives the session id for the current session.

What is the difference between $name and $$name?

$name is variable where as $$name is reference variable
like $name=sonia and $$name=singh so $sonia value is singh.

  mysql_fetch_object vs  mysql_fetch_array?

mysql_fetch_object() is similar tomysql_fetch_array(), with one difference - an object is returned, instead of an array. Indirectly, that means that you can only access the data by the field names, and not by their offsets numbers are illegal property names

In PHP for pdf which library used?. 

The PDF functions in PHP can create PDF files using the PDFlib library With version 6, PDFlib offers an object-oriented API for PHP 5 in addition to the function-oriented API for PHP 4. There is also the » Panda module. FPDF is a PHP class which allows to generate PDF files with pure PHP, that is to say without using the PDFlib library. F from FPDF stands for Free: you may use it for any kind of usage and modify it to suit your needs. FPDF requires no extension (except zlib to activate compression and GD for GIF support) and works with PHP4 and PHP5.
How  to Connecting two Strings? 
a useful concept—concatenation. It refers to the process of linking
items together. Specifically in programming, you concatenate strings.
The period . is the operator for performing this action, and it's used like so:

$tString = $String1 . $bString2;

echo $tString;

Why we use strstr?
strstr returns all of string after the first occurrence of substring .
If substring doesn't exist in string , the function returns FALSE.

How to  capitalize only the first character of a string?
you use ucfirst:
$txt = "welcome to the this site";
echo $ucfirst($txt);
What three components need to create a dynamic web page? 
A web server, a server-side programming language, and a database.

What does Apache use to load extensions?


What does the PHP Interpreter do?
 It processes the HTML and PHP files.

What's a more secure function than md5() for encoding passwords? 
The sh1() function creates a 160-bit key instead of md5()'s 128-bit string. 
It also uses a superior algorithm for making it difficult to determine the 
values that generate a particular encoding.

What are the advantages of using PEAR?
 The PEAR functions are more compact, and they automate some of the manual
 work of connecting to and selecting from the database. Because PEAR code
 is used by many developers, it is less likely to have an error than to have code
 that's written from scratch.

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Advanced PHP

find the number of parameters passed into function in PHP?

func_num_args() function returns the number of parameters/arguments passed to a function in PHP.

difference between include and require?

Answer: 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

What is SQL Injection?

SQL Injection is the hacking technique which attempts to pass SQL commands (statements) through a web application for execution by the backend database.

it can be prevented by mysql_real_escape_string() function of PHP.

Such features as login pages, support and product request forms, feedback forms, search pages, shopping carts and the general delivery of dynamic content, shape modern websites and provide businesses with the means necessary to communicate with prospects and customers.

what is ob_start?

ob_start turns on output buffering,

Scope Resolution Operator?

::  is the scope operator it is used to call methods of a class that has not been instantiated.

What is MVC?

MVC- Model, View, Controller - is simply
Model -  contains data access code and all of you business logic code.
View - Contains markup/design code, generally html,xml, json.
Controller -  contains very little code, just whatever is needed to call the Model code and render the View code.

how access a method in the parent class that's been overridden in the child?

Prefix parent:: to the method name:
class shape {
    function draw( ) {
        // write to screen

class circle extends shape {
   function draw($origin, $radius) {
      // validate data
      if ($radius > 0) {
          parent::draw( );
          return true;

      return false;

how execute different code depending on the number and type of arguments passed to a method?

PHP doesn't support method polymorphism as a built-in feature. However, you can emulate it using various type-checking functions. The following combine( ) function uses is_numeric(), is_string(), is_array(), and is_bool():
// combine() adds numbers, concatenates strings, merges arrays,
// and ANDs bitwise and boolean arguments
function combine($a, $b) {
    if (is_numeric($a) && is_numeric($b)) {
        return $a + $b;

    if (is_string($a)  && is_string($b))  {
        return "$a$b";

    if (is_array($a)   && is_array($b))   {
        return array_merge($a, $b);

    if (is_bool($a)    && is_bool($b))    {
        return $a & $b;

    return false;

want to link two objects, so when you update one, you also update the other?

Use =& to assign one object to another by reference:
$adam = new user;
$dave =& $adam;

how eliminate an object?

Objects are automatically destroyed when a script terminates. To force the destruction of an object, use unset( ):
$car = new car; // buy new car
unset($car);    // car wreck

how create a new instance of an object?

Define the class, then use new to create an instance of the class:
class user {
    function load_info($username) {
       // load profile from database

$user = new user;

exchange the values in two variables without using additional variables for storage?

To swap $a and $b:
list($a,$b) = array($b,$a);

access the values passed to a function?how

Use the names from the function prototype:
function commercial_sponsorship($letter, $number) { 
    print "This episode of Sesame Street is brought to you by ";
    print "the letter $letter and number $number.\n";

commercial_sponsorship('G', 3);
commercial_sponsorship($another_letter, $another_number);

how associate multiple elements with a single key?

Store the multiple elements in an array:
$fruits = array('red' => array('strawberry','apple'),
                'yellow' => array('banana'));
Or, use an object:
while ($obj = mysql_fetch_object($r)) {
    $fruits[ ] = $obj;

How to check whether two floating-point numbers are equal?

Use a small delta value, and check if the numbers are equal within that delta:
$delta = 0.00001;

$a = 1.00000001;
$b = 1.00000000;

if (abs($a - $b) < $delta) { /* $a and $b are equal */ }

You want to extract part of a string, starting at a particular place in the string

Use substr( ) to select your substrings:
$substring = substr($string,$start,$length);
$username = substr($_REQUEST['username'],0,8);

Php get_meta_tags-Extracts all meta tag content attributes

get_meta_tagsExtracts all meta tag content attributes from a file and returns an array

<?php// Assuming the above tags are at$tags get_meta_tags('');
// Notice how the keys are all lowercase now, and
// how . was replaced by _ in the key.
echo $tags['author'];       // nameecho $tags['keywords'];     // php documentationecho $tags['description'];  // a php manualecho $tags['geo_position']; // 49.33;-86.59?>

PHP Redirect - Redirect Script?

PHP Redirect Function

header('Location:  destination.php');
ou need the Location: part so the browser knows what header it's 
receiving. Also, don't forget to 
do an exit() or die() right after the redirect.