PHP Interview questions

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  • 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

  • What is the use of “echo” in php?

    It is used to print a data in the webpage, Example: , The following code print the text in the webpage

  • 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.

  • 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.

  • 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.

    ‘); })(); ]]>

  • 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 .

  • What is the purpose of the superglobal variable called $_SERVER ?

    $_SERVER is an array and it holds the information about paths, headers, and script locations.

  • How to Detecting request type in PHP ?

    By using $_SERVER[‘REQUEST_METHOD’] method

  • How to declare an array in php?

    Eg : var $arr = array(‘apple’, ‘grape’, ‘lemon’);

  • How can PHP interact to Javascript ?

    PHP cannot interact with javascript directly, since php is server side programming language when javascript is a client side programming language. However we can embbed the php variable values to a javascript code section when it complile at the server or javascript can communicate to a php page via http calls

    NB: Javascript can run at the server side as well using Node.js Server

  • How to manipulate image files using php ?

    GD is library that providing image manipulation capabilities to php, so that we can do so many things such as crop, merge, change grayscale and much more with GD functions

  • How to manipulate video files using php ?

    There is no inbuilt library available in php, However there are some open source libraries that providing these features

    FFmpeg is a complete, cross-platform solution to record, convert and stream audio and video. We can install this extension in php and use to do variety of tasks

  • What is cron jobs ?

    Cron jobs are scheduled tasks, executed on regular time intervals set by the developer. They work by running preferred scripts. We can set the time intervals for running these scripts. Its not a part of php compiler, We have several ways to do this based on the platform or the hostign control panel type

  • How to sent a POST request from php ( Without using any html ) ?

    You could use cURL, that allows you to connect and communicate to many different types of servers with many different types of protocols such as http, https, ftp etc.

  • How to create a directory if it doesn’t already exist ?

    if (!file_exists(‘path/to/directory’)) {
        mkdir(‘path/to/directory’, 0777, true);
        }
    ?>

  • How to delete an element from an array ?

    If you want to just delete a single element you can use unset() or alternatively array_splice().

    unset() method won’t change array key when array_splice() method change the array keys automatically

  • 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 ‘);

  • What is use of in_array() function in php ?

    in_array used to checks if a value exists in an array

  • What is use of count() function in php ?

    count() is used to count all elements in an array, or something in an object

  • 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?

    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

  • How to set cookies in PHP?

    Setcookie(“sample”, “ram”, time()+3600);

  • How to Retrieve a Cookie Value?

    eg : echo $_COOKIE[“user”];

  • 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’];

  • what types of loops exist in php?

    for,while,do while and foreach (NB: You should learn its usage)

  • Note:-

    MySQLi (the “i” stands for improved) and PDO (PHP Data Objects) are the MySQL extensions used to connect to the MySQL server in PHP5 or verions, MySQL extension was deprecated in 2012.

    MySQLi only works with MySQL databases whereas PDO will works with 12 other Database systems

    I recommend PDO because, if you want to choose another database instead of MySQL, then you only have to change the connection string and a few queries. But if you are using MySQLi you will need to rewrite the entire code

  • How to create a mysql connection?
    Example (PDO)

    $servername = “localhost”;
    $username = “username”;
    $password = “password”;

    try {
        $conn = new PDO(“mysql:host=$servername;dbname=myDB”, $username, $password);
        // set the PDO error mode to exception
        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        echo “Connected successfully”;
        }
    catch(PDOException $e)
        {
        echo “Connection failed: ” . $e->getMessage();
        }
    ?>

    Example (MySQLi Object-Oriented)

    $servername = “localhost”;
    $username = “username”;
    $password = “password”;
    $dbname = “myDB”; // Optional

    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);

    // Check connection
    if ($conn->connect_error) {
        die(“Connection failed: ” . $conn->connect_error);
    }
    echo “Connected successfully”;
    ?>

    Example (MySQLi Procedural)

    $servername = “localhost”;
    $username = “username”;
    $password = “password”;
    $dbname = “myDB”; // Optional

    // Create connection
    $conn = mysqli_connect($servername, $username, $password, $dbname);

    // Check connection
    if (!$conn) {
        die(“Connection failed: ” . mysqli_connect_error());
    }
    echo “Connected successfully”;
    ?>

  • What are prepared statements?

    A prepared statement or a parameterized statement is a feature used to execute the same SQL queries repeatedly with high efficiency. It consists of two stages: prepare and execute. Prepared statements reduce parsing time because preparation on the query is done only once while the statement is executed multiple times. It is very useful against SQL injections because parameter values won’t alter objective of the statement.

  • How to execute an sql query? How to fetch its result ?
    Example (MySQLi Object-oriented)

    $sql = “SELECT id, firstname, lastname FROM MyGuests”;
    $result = $conn->query($sql); // execute sql query

    if ($result->num_rows > 0) {
        // output data of each row
        while($row = $result->fetch_assoc()) { // fetch data from the result set
            echo “id: ” . $row[“id”]. ” – Name: ” . $row[“firstname”]. ” ” . $row[“lastname”]. “
    “;
        }
    } else {
        echo “0 results”;
    }

    Example (MySQLi Procedural)

    $sql = “SELECT id, firstname, lastname FROM MyGuests”;
    $result = mysqli_query($conn, $sql); // execute sql query

    if (mysqli_num_rows($result) > 0) {
        // output data of each row
        while($row = mysqli_fetch_assoc($result)) { // fetch data from the result set
            echo “id: ” . $row[“id”]. ” – Name: ” . $row[“firstname”]. ” ” . $row[“lastname”]. “
    “;
        }
    } else {
        echo “0 results”;
    }

    Example (PDO)

    Method 1:USE PDO query method

    $stmt = $db->query(‘SELECT id FROM Employee’);
    $row_count = $stmt->rowCount();
    echo $row_count.’ rows selected’;

    Method 2: Statements With Parameters

    $stmt = $db->prepare(“SELECT id FROM Employee WHERE name=?”);
    $stmt->execute(array($name));
    $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);

  • Write a program using while loop $x = 1;

    while($x <= 5) {
        echo “The number is: $x
    “;
        $x++;
    }
    ?>

  • How we can retrieve the data in the result set of MySQL using PHP?
    MySQLi methods
    • 1. mysqli_fetch_row
    • 2. mysqli_fetch_array
    • 3. mysqli_fetch_object
    • 4. mysqli_fetch_assoc
    PDO methods
    • 1. PDOStatement::fetch(PDO::FETCH_ASSOC)
    • 2. PDOStatement::fetch(PDO::FETCH_OBJ)
    • 3. PDOStatement::fetch()
    • 4. PDOStatement::fetch(PDO::FETCH_NUM)
  • What is the use of explode() function ?

    Syntax : array explode ( string $delimiter , string $string [, int $limit ] );
    This function breaks a string into an array. Each of the array elements is a substring of string formed by splitting it on boundaries formed by the string delimiter.

  • What is the difference between explode() and str_split() functions?

    str_split function splits string into array by regular expression. Explode splits a string into array by string.

  • What is the use of mysqli_real_escape_string() function?

    It is used to escapes special characters in a string for use in an SQL statement

  • Write down the code for save an uploaded file in php.

    if ($_FILES[“file”][“error”] == 0)
    {
    move_uploaded_file($_FILES[“file”][“tmp_name”],
          “upload/” . $_FILES[“file”][“name”]);
          echo “Stored in: ” . “upload/” . $_FILES[“file”][“name”];
    }
    ?>

  • How to create a text file in php?

    $filename = “/home/user/guest/newfile.txt”;
    $file = fopen( $filename, “w” );
    if( $file == false )
    {
    echo ( “Error in opening new file” ); exit();
    }
    fwrite( $file, “This is a simple testn” );
    fclose( $file );
    ?>

  • 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 used for it, header(“Location:index.php”);

  • How stop the execution of a php scrip ?

    exit() function is used to stop the execution of a page

  • 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

  • How to find the length of a string?

    strlen() function used to find the length of a string

  • 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.

  • what is the use of isset() in php?

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

  • What is the difference between mysqli_fetch_array() and mysqli_fetch_assoc() ?

    mysqli_fetch_assoc function Fetch a result row as an associative array, While mysqli_fetch_array() fetches an associative array, a numeric array, or both

  • What is mean by an associative array?

    Associative arrays are arrays that use string keys is called associative arrays.

  • 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.

  • 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.

  • 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

  • How to create an array of a group of items inside an HTML form ?

    We can create input fields with same name for “name” attribute with squire bracket at the end of the name of the name attribute, It passes data as an array to PHP.
    For instance :




  • Define Object-Oriented Methodology

    Object orientation is a software programming methodology that is based on the modeling a real world system.An object is the core concept involved in the object orientation. An object is the copy of the real world enity.An object oriented model is a collection of objects and its inter-relationships

  • How do you define a constant?

    Using define() directive, like define (“MYCONSTANT”,150)

  • How send email using php?

    To send email using PHP, you use the mail() function.This mail() function accepts 5 parameters as follows (the last 2 are optional). You need webserver, you can’t send email from localhost. eg :

    mail($to,$subject,$message,$headers);
    ?>

    mcrypt_encrypt :- string mcrypt_encrypt ( string $cipher , string $key , string $data , string $mode [, string $iv ] );
    Encrypts plaintext with given parameters

  • How to find current date and time?

    The date() function provides you with a means of retrieving the current date and time, applying the format integer parameters indicated in your script to the timestamp provided or the current local time if no timestamp is given. In simplified terms, passing a time parameter is optional – if you don’t, the current timestamp will be used.

  • How to find the number of days between two dates ?

    $now = time(); // or your date as well
    $your_date = strtotime(“2010-01-31”);
    $datediff = $now – $your_date;
    echo round($datediff / (60 * 60 * 24));
    ?>

  • How to convert one date format into another in PHP ?

    $old_date = date(‘l, F d y h:i:s’); // returns Saturday, January 30 10 02:06:34
    $old_date_timestamp = strtotime($old_date);
    $new_date = date(‘Y-m-d H:i:s’, $old_date_timestamp);
    ?>

  • What is the use of “ksort” in php?

    It is used for sort an array by key in reverse order.

  • What is the difference between $var and $$var?

    They are both variables. But $var is a variable with a fixed name. $$var is a variable who’s name is stored in $var. For example, if $var contains “message”, $$var is the same as $message.

  • What are the encryption techniques in PHP

    MD5 PHP implements the MD5 hash algorithm using the md5 function,

    $encrypted_text = md5 ($msg);
    ?>

  • What is the use of the function htmlentities?

    htmlentities Convert all applicable characters to HTML entities This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.

  • How to delete a file from the system

    Unlink() deletes the given file from the file system.

  • How to get the value of current session id?

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

  • What are the differences between mysqli_fetch_array(), mysqli_fetch_object(), mysqli_fetch_row()?
    • Mysqli_fetch_array Fetch a result row as an associative array, a numeric array, or both.
    • mysqli_fetch_object ( resource result ) Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows
    • mysqli_fetch_row() fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.
  • Why we shouldn’t use mysql_* functions in PHP?
    • Is not under active development
    • Is officially deprecated as of PHP 5.5 (released June 2013).
    • Has been removed entirely as of PHP 7.0 (released December 2015)
  • What are the different types of errors in PHP ?

    Here are three basic types of runtime errors in PHP:

    • 1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although you can change this default behavior.
    • 2. Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
    • 3. Fatal errors: These are critical errors – for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behavior is to display them to the user when they take place.
  • what is sql injection ?

    SQL injection is a malicious code injection technique.It exploiting SQL vulnerabilities in Web applications

  • What is x+ mode in fopen() used for?

    Read/Write. Creates a new file. Returns FALSE and an error if file already exists

  • How to find the position of the first occurrence of a substring in a string

    strpos() is used to find the position of the first occurrence of a substring in a string

  • What is PEAR?

    PEAR is a framework and distribution system for reusable PHP components.The project seeks to provide a structured library of code, maintain a system for distributing code and for managing code packages, and promote a standard coding style.PEAR is broken into three classes: PEAR Core Components, PEAR Packages, and PECL Packages. The Core Components include the base classes of PEAR and PEAR_Error, along with database, HTTP, logging, and e-mailing functions. The PEAR Packages include functionality providing for authentication, networking, and file system features, as well as tools for working with XML and HTML templates.

  • Distinguish between urlencode and urldecode?

    This method is best when encode a string to used in a query part of a url. it returns a string in which all non-alphanumeric characters except -_. have replece with a percentege(%) sign . the urldecode->Decodes url to encode string as any %and other symbole are decode by the use of the urldecode() function.

  • What are the different errors in PHP?

    In PHP, there are three types of runtime errors, they are:

    Warnings:
    These are important errors. Example: When we try to include () file which is not available. These errors are showed to the user by default but they will not result in ending the script.
    Notices:
    These errors are non-critical and trivial errors that come across while executing the script in PHP. Example: trying to gain access the variable which is not defined. These errors are not showed to the users by default even if the default behavior is changed.
    Fatal errors:
    These are critical errors. Example: instantiating an object of a class which does not exist or a non-existent function is called. These errors results in termination of the script immediately and default behavior of PHP is shown to them when they take place. Twelve different error types are used to represent these variations internally.

  • What is a REST API?

    An API is an interface which can be a program or a web application which is capable to communicate to other websites or programs

    REST stands for REpresentational State Transfer and is an architectural style for exposing your program using existing protocols, typically HTTP

    A REST API utilize HTTP Methods like GET/POST/DELETE/UPDATE etc to get or set data in a server

  • Give me the list of function you are usually using when you debug your PHP scripts ?

    During the development time, i will put error_reporting(E_ALL); ini_set(‘display_errors’, 1); on the top of the php script to display all the errors and notices.

    I will use print_r, var_dump functions to debug logical errors, there are so many other function also available for the same.

  • What are magic constants in PHP?

    Magic constants are predefined constants which starts and ends with double underscore (__).

    Following are some of the magic constants.

    • __LINE__
    • __FUNCTION__
    • __CLASS__
    • __FILE__
    • __METHOD__
  • Does PHP support multiple inheritance ?

    PHP does not support multiple inheritance it will support only single inheritance. We can use the keyword extent a class from another class

  • What is the use of print_r function?

    print_r function can be used to display human readable format of an array

  • What happened if we pass ‘0’ as the parameter to set_time_limit() function ?

    It will set the the execution time as infinite

  • How to store the content of a file in to a a string variable?

    File get contents function can be e used to to read the content of a file and save the the data into a variable

  • How to find the number of rows returned from a MySQL result set?

    mysqli_num_rows function can be used to find the number of rows of a rasult set

  • What is the difference between the empty() and isset() ?

    isset() function is used to check available is already declared or not while empty() function is used to check weather the variable has a value or not

  • What is the use of the key word global ?

    If we declare a variable as ‘global’ then we can access it within the PHP functions

  • How to get the current memory usage in PHP?

    memory_get_usage function can be used to get the memory usage information

  • What is scalar type declarations in in PHP 7?

    It’s a new feature in PHP 7 we can declare scalar types like inch string bullion fraught

  • Explain anonymous classes in PHP 7?

    Anonymous classes does not require any name this anonymous classes can be e defined using the new class. It will internal generate class names so we don’t have to to give names to the classes. IT can replace ful class definition.

  • How to collect  IP address from an HTTP request ? 

    $_SERVER[‘REMOTE_ADDR’];

  • How to collect  IP address of the Web server in php ? 

    $_SERVER[‘SERVER_ADDR’];

  • How to enable error reporting ?

    error_reporting(E_ALL);

  • What is $_GLOBAL ?

    It is an associative array which containing references to all variables currently defined in the global scope of the script.

  • What is .htaccess file ?

    .htaccess is a configuration file used to alter the default behavior of a Apache web server software. Most common usage is to redirect the http request to some URLs based on some conditions. For example, we can hide the .html or .php extensions of the URLs to make it SEO friendly

  • How to print structured information about a available in PHP ?

    var_dump — This function displays structured information about one or more expressions that includes its value and type. Objects and arrays are explored recursively with values indented to show structure.

    Usage   var_dump($a);

  • What is the difference between var_dump and print_r ?

    var_dump will display all the information of a variable including keys values and types while print_r display the keys and values only in a human readable format.

  • What is automatic type conversion ?

    In php we can declare variables without specifying its type, php it do that process automatically since PHP is a loosely types language.

    For example : 

    //$count is a string variable
    $count = “5”;
    //$count is an int variable
    $count = “5”;

  • How to make API calls from php scripts ?

    We can use cURL library to make HTTP calls from a php script

    $ch = curl_init();
    $postData = ‘var1=value1&var2=value2&var3=value3’;
    curl_setopt($ch, CURLOPT_URL, “http://mydomain.com/ajaxurl”;);
    curl_setopt($ch, CURLOPT_POST, 1 );
    curl_setopt($ch, CURLOPT_POSTFIELDS, $postData );
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true );
    $ch = curl_exec($ch);
    $ch = curl_close($ch);
    echo $result;die;

  • How to change the php configurations at run time ?

    We can use `ini_set` function to change the configurations of php at run time.

  • How can we resolve the errors like ‘Maximum execution time of 30 seconds exceeded’ ?

    We can use the following code to increase the maximum execution time of the script 

    ini_set(‘max_execution_time’, 300);

    We can also set the max_execution_time for all the scripts in a website by the following code in .htaccess file

    php_value max_execution_time 300   

    But, we must try to optimize the php script to avoid this kind of situations as a part good user experience.

  • How to avoid email sent through php getting into spam folder?

    There’s no special method of keeping your emails from being identified as spam. However we can consider some points that cause this problem. Let me explain few common reasons.

    1. sending mail using the `mail` function with minimum parameters

        We must use all possible mail headers like `MIME-version`, `Content-type`, `reply address`, `from address` etc in order to avoid this situation

    2. Not using a proper SMTP mail script like PHPmailer or SwiftMailer with an actual e-mail credentials including username, password etc

        If we are able to send e-mail from an actual e-mail account using an SMTP mailer script with username and password, then we can avoid  

    If you’re on a shared web server, consider buying a unique IP address for yourself, because others using your IP may have gotten your IP blacklisted for spam. Do not send more than 250 emails to each provider per hour.

    Give your users unsubscribe link and view in browser link, if they cannot see the email properly they will mark you as spam, if they no longer want emails for you they will mark you as spam. 

    How can we prevent SQL injection in PHP?

    Most popular way is, use prepared statements and parameterized queries. These are SQL statements that are sent to and parsed by the database server separately from any parameters. This way it is impossible for an attacker to inject malicious SQL.

    You basically have two options to achieve this:

    1. Using PDO (for any supported database driver):

      $stmt = $pdo->prepare(‘SELECT * FROM employees WHERE name = :name’); $stmt->execute(array(‘name’ => $name)); foreach ($stmt as $row) { // do something with $row }

    2. Using MySQLi (for MySQL):

      $stmt = $dbConnection->prepare(‘SELECT * FROM employees WHERE name = ?’);
      $stmt->bind_param(‘s’, $name); $stmt->execute(); $result = $stmt->get_result(); while ($row = $result->fetch_assoc()) { // do something with $row } If you’re connecting to a database other than MySQL, there is a driver-specific second option that you can refer to (e.g. pg_prepare() and pg_execute() for PostgreSQL). PDO is the universal option.

  • How to fix “Headers already sent” error in PHP ?

    No output before sending headers. there should not be any output (i.e. echo.. or HTML codes) before the header(…….);command. remove any white-space(or newline) before  tags. After header(…); you must use exit;

  • How to return JSON from a PHP Script ?

    We have to set the Content-Type header with application/json  as the value and print a valid JSON data using echo method

    For example

    $data = /** whatever you’re serializing **/; header(‘Content-Type: application/json’); echo json_encode($data);

  • How can we fix “Memory size Exhausted” errors ?

    You can fix it at run time or can be set required size on the php.ini file

    ini_set(‘memory_limit’, ‘512M’); // In a php script at run time

  • When to use self over $this?

    Use $this to refer to the current object. Use self to refer to the current class. In other words, use $this->member for non-static members, use self::$member for static members.

  • How to redirect the user to one page to another using php ?

    we have a special php function called header, can be used to do the same header(“Location: new-page.php”);. We already defined the step for the same in our blog post How to php redirect

  • What is CSS?

    CSS Stands for Cascading Style Sheets. It is a platform independent web page designing language and it will saves time because we can write this once and use the same in other pages.

  • What are the ways to integrate css in a web page

    There are three ways to integrate css in a web page

    • Inline : It is used to Apply some styles to an element including its child elements using style attribute
    • Embedded : We can write group of styles with in the html

      tag

    • Linked/ Imported : We can specify an external stylesheet url using the following code
  • Listout some widely using CSS Measurement Units

    • px – Defines a measurement in screen pixels.
    • % – Defines a measurement as a percentage relative to another value, mainly an enclosing element.
    • em – It is a relative measurement for the height of a font used in em spaces in a web page. Because 1em unit is equivalent to the size of a given font, if you assign a font to 10pt, each “em” unit would be 10pt; thus, 2em would be 20pt.
    • vh – 1% of viewport height, Viewport measurements are very useful when developing a responsive web page or Hybrid App.
    • vw – 1% of viewport height.
    • vw – 1% of viewport height.
  • Which property allows you to control the shape or appearance of the marker of a list?

    The list-style-type allows you to control the shape or appearance of the marker.

  • Which property specifies whether a long point that wraps to a second line should align with the first line or start underneath the start of the marker of a list?

    The list-style-position specifies whether a long point that wraps to a second line should align with the first line or start underneath the start of the marker.

  • Which property specifies an image rather than a bullet point or number for the marker of a list?

    The list-style-image specifies an image for the marker rather than a bullet point or number.

  • Which property serves as shorthand for the styling properties of a list?

    The list-style serves as shorthand for the styling properties.

  • Which property specifies the distance between a marker and the text in the list?

    The marker-offset specifies the distance between a marker and the text in the list.

  • Which property specifies the bottom padding of an element?

    The padding-bottom specifies the bottom padding of an element.

  • Which property specifies the top padding of an element?

    The padding-top specifies the top padding of an element.

  • Which property specifies the left padding of an element?

    The padding-left specifies the left padding of an element.

  • Which property specifies the right padding of an element?

    The padding-right specifies the right padding of an element.

  • Which property serves as shorthand for the all the padding properties of an element?

    The padding serves as shorthand for the all the padding properties.

  • Which property allows you to specify the type of cursor that should be displayed to the user?

    The cursor property of CSS allows you to specify the type of cursor that should be displayed to the user.

  • Which value of cursor property changes the cursor based on context area it is over?

    auto − Shape of the cursor depends on the context area it is over. For example, an ‘I’ over text, a ‘hand’ over a link, and so on.

  • Which property is used to set all the outlining properties in a single statement?

    The outline property is used to set all the outlining properties in a single statement.

  • Which property is used to set the height of a box?

    The height property is used to set the height of a box.

  • Which property is used to set the width of a box?

    The width property is used to set the width of a box.

  • Why is @import only at the top?

    @import is preferred only at the top, to avoid any overriding rules. Generally, ranking order is followed in most programming languages such as Java, Modula, etc. In C, the # is a prominent example of a @import being at the top.

  • What is contextual selector?

    Selector used to select special occurrences of an element is called contextual selector. A space separates the individual selectors. Only the last element of the pattern is addressed in this kind of selector. For e.g.: TD P TEXT {color: blue}

  • How html5 is different from html4?

    HTML5 is an upgraded version of html4.01 and introduced some new features such as Audio, Video, Canvas, Drag & Drop, Storage, Geo Location, Web Socket etc and also introduced some new html tags such as article, section, header, aside and nav etc which help to create the page layout faster. HTML 5 will handle the inaccurate syntax of the tags and it simplified the doctype and character set declaration. It also deprecated some html tags like center, font, strike, acronym, applet etc.

  • How browsers detect the html version of a webpage?

    We must declare the doctype at the top of the page, it is an instruction to the web browser about what version of HTML the page is written in.

  • Write down the Doctype declaration of html5 and html4

    html5

    html4

  • What are the new form attributes in HTML5 ?

    Placeholder, novalidate, autocomplete, required , autofocus, pattern, list, multiple, formnovalidate etc

  • What are the different units for expressing a length in css?

    rem, vh, vw, ex, ch, em, %, px, in, cm, mm, pt and pc

    Unit Description
    em 1 em is the computed value of the font-size on the element on which it is used.
    ex 1 ex is the current font’s x-height. The x-height is usually (but not always, e.g., if there is no ‘x’ in the font) equal to the height of a lowercase ‘x’
    ch 1 ch is the advance of the ‘0’ (zero) glyph in the current font. ‘ch’ stands for character.
    rem 1 rem is the computed value of the font-size property for the document’s root element.
    vw 1vw is 1% of the width of the viewport. ‘vw’ stands for ‘viewport width’.
    vh 1vh is 1% of the height of the viewport. ‘vh’ stands for ‘viewport height’.
    vmin Equal to the smaller of ‘vw’ or ‘vh’
    vmax Equal to the larger of ‘vw’ or ‘vh’
  • What is SVG?

    SVG stands for Scalable Vector Graphics, It is an XML based two-dimensional vector graphics image format.

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  • What is character encoding in HTML ?

    Character encoding is a rule for how to interpret raw zeroes and ones into real characters. There are two main character encoding representations used in html documnets such as UTF-8, and ISO-8859-1. The default character set for HTML5 is UTF-8. The following syntax is used to set the character encoding in an html document

  • What is HTML Entities ?

    HTML Entities are some special words which is used to replace the reserved characters or some other characters that are not present on your keyboard can also be replaced by entities in your HTML, For example if you need to display < ( 'Less than' symbol ) In your html document, You can use < Entity

  • What is mean by Responsive Web Site ?

    It will looks good in all screen resolutions device type. We can utilize css media quries to re-arrange the with of an element also we can hide or display any elements in a web page. Bootstrap is a widely using css framework to make responsive web pages quikly

  • List out some HTML5 tags

    header, footer, main, nav, section, article, aside etc..

  • What is the use of HTML5 Canvas element ?

    It is used to draw graphics on a web page by the help of javascript.

  • What is the use of ‘placeholder’ attribute in HTML5?

    It is used to display some text with in a textbox or textarea and the text will disappear when user start typing in that box

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