Day 10 - Let's Eat Cookie - Become PHP Expert in 30 days

Let's Eat Cookie

http://webhostingneeds.com/tmp_fp/php_day_10.jpg

In our Day 9 code (day_9_ex_1.php) we used POST method, so you won't be able to see the secret number server generated by looking at URL. But if you look source code of the page, you still able to see the secret number.

Viewing Source Code

You can view source code of any web page by pressing

Code:

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CTRL+U

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http://webhostingneeds.com/tmp_fp/ph...rce_chrome.jpg

This will only show HTML code. It won't show any PHP code as PHP is running in server side.

http://webhostingneeds.com/tmp_fp/ph...iew_source.jpg

From the source code, you can see the hidden INPUT field stores the secretNumber.

Code:

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<input type="hidden" name="secretNumber" value="27">

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How can we remove this number from the HTML code, so no one will be able to see it by viewing source code of our HTML page ? We can do this with the help of COOKIE.

What is COOKIE

Cookie is used to store information on visitors computer. Some sites can remember you, so you don't have to login to these site every time because they store a COOKIE on your computer, next time when you visit these sites, web server read the data stored in these COOKIE and authenticate you.

Data stored in cookie are more difficult to read (not impossible) for most users. Also most sites store encrypted value in the cooke, so even if someone read cookie, they won't be able to know what is stored in the cookie.

Let's make a script, that will store your name in cookie. Greet you when you visit the page again.

day_10_ex_1.php

PHP Code:

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<?php

if (isset($_COOKIE['phpExpertName'])) {
    echo $_COOKIE['phpExpertName'] . ', Welcome to Bakery, eat some $_COOKIE';
    exit;
}

if (isset($_POST['phpExpertName']) && strlen($_POST['phpExpertName']) > 3) {
    // time()+3600 = 1 hour, that is cookie will remember your name for 1 hour.
    // time() is a PHP function, that return current time in numeric format.
    // 3600 == number of seconds in 1 hour.
    // So to remember 2 hour, use time() + 3600 * 2
    setcookie('phpExpertName', $_POST['phpExpertName'], time()+3600);
    echo 'Cookie Set. Close the browser. Revisit this page, I will remember your name';
} else {

    echo '
        What is your name ?
        <form method="post" action="">
        <input type="text" name="phpExpertName">
        <button type="submit" name="whatever">Enter Web Site</button>
        </form>
    ';
}

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setcookie() function is used to set cookie. setcookie() must be called before any echo statement.

You will be able to read data stored in cookie using associative array $_COOKIE.

How to Delete A Cookie

A cookie can be delete by setting cookie expiry time to 0.

day_10_ex_2.php

PHP Code:

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<?php

setcookie('phpExpertName', '', 0);
echo 'Cookie deleted.';
echo '<br>';
echo 'Visit day_10_ex_1.php, you will see the script will ask you name again, because no cookie is set.';

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http://webhostingneeds.com/tmp_fp/php-back-btn.jpg

http://php.flashwebhost.com/melbin/set_cookie.php

PHP Code:

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<?php

if (isset($_COOKIE['VisitorName'])) {
    echo 'Hi ' . $_COOKIE['VisitorName'];
    exit;
}

if (isset($_POST['VisitorName']) && strlen($_POST['VisitorName']) > 3) {
    setcookie('VisitorName', $_POST['VisitorName'], time() + (86400 * 7)); // Remember 1 week
    echo 'Cookie Set. Close the browser. Revisit this page, I will remember your name for 1 week';
} else {

    echo '
        What is your name ?
        <form method="post" action="">
        <input type="text" name="VisitorName">
        <button type="submit" name="Submit">Remember Me</button>
        </form>
    ';
}

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I am getting the following warning message

Code:

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Warning: Cannot modify header information - headers already sent by (output started at /home/fwhphp/public_html/melbin/set_cookie.php:1) in /home/fwhphp/public_html/melbin/set_cookie.php on line 9

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Why ??

Remove empty line from line number 1.

setcookie() function should be called before outputting any text to browser.

http://php.flashwebhost.com/sherly/cookies.php

Code:

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<?php

if (isset($_COOKIE['bakery_visitor'])) {
    echo $_COOKIE['bakery_visitor'] . ', Welcome to Himalaya Bakery, eat some $_COOKIE';
    exit;
}

if (isset($_POST['bakery_visitor']) && strlen($_POST['bakery_visitor']) > 5) {
    // time()+2800 = 2 hour, that is cookie will remember your name for 2 hour.
    // time() is a PHP function, that return current time in numric format.
    // 2800 == number of seconds in 2 hour.
    // So to remember 4 hour, use time() + 2800 * 4
    setcookie('bakery_visitor', $_POST['bakery_visitor'], time()+2800);
    echo 'Cookie Set. Close the browser. Revisit this page, I will remember your name';
} else {

    echo '
        What is your name ?
        <form method="post" action="">
        <input type="text" name="bakery_visitor">
        <button type="submit" name="whatever">Enter your name</button>
        </form>
    ';
}

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Quote:

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Originally Posted by sherlyk

http://php.flashwebhost.com/sherly/cookies.php

Code:

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<?php

if (isset($_COOKIE['bakery_visitor'])) {
    echo $_COOKIE['bakery_visitor'] . ', Welcome to Himalaya Bakery, eat some $_COOKIE';
    exit;
}

if (isset($_POST['bakery_visitor']) && strlen($_POST['bakery_visitor']) > 5) {
    // time()+2800 = 2 hour, that is cookie will remember your name for 2 hour.
    // time() is a PHP function, that return current time in numric format.
    // 3600 == number of seconds in 2 hour.
    // So to remember 4 hour, use time() + 2800 * 4
    setcookie('bakery_visitor', $_POST['bakery_visitor'], time()+2800);
    echo 'Cookie Set. Close the browser. Revisit this page, I will remember your name';
} else {

    echo '
        What is your name ?
        <form method="post" action="">
        <input type="text" name="bakery_visitor">
        <button type="submit" name="whatever">Enter your name</button>
        </form>
    ';
}

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Good, working perfectly.

http://php.flashwebhost.com/annie/cookie.php

Code:

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<?php
if (isset($_COOKIE['visitor_name'])) {
echo $_COOKIE['visitor_name'] . ', Welcome to Meritnation';
exit;
}

if (isset($_POST['visitor_name']) && strlen($_POST['visitor_name']) > 3) {
setcookie('visitor_name',$_POST['visitor_name'], time() + 18000);
echo 'Cookie Set. Close the browser. Revisit this page, I will remember your name';
} else {
 echo '
        What is your name ?
        <form method="post" action="">
        <input type="text" name="visitor_name">
        <button type="submit" name="submit">Enter Web Site</button>
        </form>
    ';
}

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Quote:

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Originally Posted by annie

http://php.flashwebhost.com/annie/cookie.php

Code:

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<?php
if (isset($_COOKIE['visitor_name'])) {
echo $_COOKIE['visitor_name'] . ', Welcome to Meritnation';
exit;
}

if (isset($_POST['visitor_name']) && strlen($_POST['visitor_name']) > 3) {
setcookie('visitor_name',$_POST['visitor_name'], time() + 18000);
echo 'Cookie Set. Close the browser. Revisit this page, I will remember your name';
} else {
 echo '
        What is your name ?
        <form method="post" action="">
        <input type="text" name="visitor_name">
        <button type="submit" name="submit">Enter Web Site</button>
        </form>
    ';
}

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Nice script, working properly.

Do we need to use _ ( Underscore ) if our variable have three words ?
php_expert_name

Before we used like

secretNumber
userNumber
cowsCanFly

Any difference between these two variable type?

Quote:

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Originally Posted by sibichan1

Do we need to use _ ( Underscore ) if our variable have three words ?
php_expert_name

Before we used like

secretNumber
userNumber
cowsCanFly

Any difference between these two variable type?

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It is better we follow one type of coding style. So far PHP had no coding guidelines like many other programming languages. So we used whatever we like, but when working on a team, it is better we follow same coding conventions. In vShare, we use $video_info, $user_name etc.. At that time no such coding guidelines where present and we follow that rule in out code.

Now PHP have a coding style

http://www.php-fig.org/psr/psr-2/

This coding style is supported by many large projects as you can see on home page of that site

http://www.php-fig.org/

Laravel, Zend Framework 2, Symfony2, Joomla, Drupal, eZ Publish, phpBB, Doctrine, CakePHP, Composer and many more. This list include popular PHP frameworks like Zend, Symfony and Laravel.

But we can't change coding style of exisiting project in one day, there are lot of code to change, so it may take time, for newer code, it is better follow a coding style, so everyone do the same, not what each programmer like, this may it easy to read/understand code.

In the code, i used

Code:

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$_COOKIE['php_expert_name']

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It is better follow the PHP variable naming convention and use

Code:

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$_COOKIE['phpExpertName']

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I will update the script to avoid further confusion.

http://php.flashwebhost.com/stefin/set_cookie.php

Code:

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<?php


if (isset($_COOKIE['flipkartCustomer'])) {
    echo $_COOKIE['flipkartCustomer'] . ',Welcome to flipkart, SPECIAL OFFER- 50% OFF ON ALL GAMES';
exit;
}


if (isset($_POST['flipkartCustomer']) && strlen($_POST['flipkartCustomer']) > 5) {
  setcookie('flipkartCustomer', $_POST['flipkartCustomer'], time()+3600);
  echo 'COOKIE Set. Close the browser. Revisit this page, I will remember your name';
} else {


echo'
    Enter your name ?
    <form method="post" action="">
    <input type="text" name="flipkartCustomer">
    <button type="submit" name="whatever">Enter Name</button>
  ';
}

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