Question

Identify and correct the error in each of the following PHP code examples:

a) <?php print( "Hello World" ); >

b) <?php
$name = "Paul";
print( "$Name" );
?>

Describe how input from an HTML5 form is retrieved in a PHP program.

Describe how cookies can be used to store information on a computer and how the information
can be retrieved by a PHP script. Assume that cookies are not disabled on the client.

Answer 1

a) The correct code is:

<?php
print "Hello World";
?>

b) The correct code is:

<?php
$name = "Paul";
print $Name;
?>

2)

How to retrieve form data sent via GET

When you submit a form through the GET method, PHP provides a superglobal variable, called $_GET. PHP uses this $_GET variable to create an associative array with keys to access all the sent information ( form data ). The keys is created using the element's name attribute values.

The $_GET Method Script: get-method.php

 // Check if the form is submitted if ( isset( $_GET['submit'] ) ) { // retrieve the form data by using the element's name attributes value as key $firstname = $_GET['firstname']; $lastname = $_GET['lastname']; // display the results echo '<h3>Form GET Method</h3>'; echo 'Your name is ' . $lastname . ' ' . $firstname; exit;
}

The GET method

 <form action="get-method.php" method="get"> <input type="text" name="firstname" placeholder="First Name" /> <input type="text" name="lastname" placeholder="Last Name" /> <input type="submit" name="submit" /> </form> 

Now let's take a look at the code ...

The PHP isset() function is used to determine if a variable is set and is not null.

Firstly, the isset() function checks if the form has been submitted by using the element's name attribute value "submit" (name="submit") as key and pass it to the $_GET[] superglobal variable. This is because the form data are stored in the $_GET[] superglobal array by PHP when it is submitted through the GET method.

Then the form field, first name and last name form data are retrieved by using the same method, passing their respective name attribute values into the $_GET['name as key'] array parameter, and each is assigned to a variable name that was used to display the results.

Using the POST

The form POST method sends information via HTTP header. All name/value pairs sent through this method is invisible to anyone else since all the information are embedded within the body of the HTTP request.

When you submit a form to a server through the POST method, PHP provides a superglobal variable called $_POST. The $_POST variable is used by PHP to create an associative array with an access key ($_POST['name as key']). The key is created automatically by PHP when the form is submitted. PHP uses the form field element name attribute (name="unique-name-here") to create the key.

The $_POST Method Script: post-method.php

// Check if the form is submitted if ( isset( $_POST['submit'] ) ) { // retrieve the form data by using the element's name attributes value as key $firstname = $_POST['firstname']; $lastname = $_POST['lastname']; // display the results
echo '<h3>Form POST Method</h3>'; echo 'Your name is ' . $lastname . ' ' . $firstname; exit; } 

The POST method form

 <form action="post-method.php" method="post">

<input type="text" name="firstname" placeholder="First Name" />

<input type="text" name="lastname" placeholder="Last Name" />

<input type="submit" name="submit" />
</form> 

3)

Creating Cookies

Let’s now look at the basic syntax used to create a cookie.

<?php

setcookie(cookie_name, cookie_value, [expiry_time], [cookie_path], [domain], [secure], [httponly]);

?>

HERE,

• Php“setcookie” is the PHP function used to create the cookie.
• “cookie_name” is the name of the cookie that the server will use when retrieving its value from the $_COOKIE array variable. It’s mandatory.
• “cookie_value” is the value of the cookie and its mandatory
• “[expiry_time]” is optional; it can be used to set the expiry time for the cookie such as 1 hour. The time is set using the PHP time() functions plus or minus a number of seconds greater than 0 i.e. time() + 3600 for 1 hour.
• “[cookie_path]” is optional; it can be used to set the cookie path on the server. The forward slash “/” means that the cookie will be made available on the entire domain. Sub directories limit the cookie access to the subdomain.
• “[domain]” is optional, it can be used to define the cookie access hierarchy i.e. www.cookiedomain.com means entire domain while www.sub.cookiedomain.com limits the cookie access to www.sub.cookiedomain.com and its sub domains. Note it’s possible to have a subdomain of a subdomain as long as the total characters do not exceed 253 characters.
• “[secure]” is optional, the default is false. It is used to determine whether the cookie is sent via https if it is set to true or http if it is set to false.
• “[Httponly]” is optional. If it is set to true, then only client side scripting languages i.e. JavaScript cannot access them.

Let’s now look at an example that uses cookies.

We will create a basic program that allows us to store the user name in a cookie that expires after ten seconds.

The code below shows the implementation of the above example “cookies.php”.

<?php
     setcookie("user_name", "Guru99", time()+ 60,'/'); // expires after 60 seconds
     echo 'the cookie has been set for 60 seconds';
?>

Output:

the cookie has been set for 60 seconds

Retrieving the Cookie value

Create another file named “cookies_read.php” with the following code.

<?php
     print_r($_COOKIE);    //output the contents of the cookie array variable 
?>

Output:

Array ( [PHPSESSID] => h5onbf7pctbr0t68adugdp2611 [user_name] => Guru99 )

Note: $_COOKIE is a PHP built in super global variable.

It contains the names and values of all the set cookies.

The number of values that the

$_COOKIE array can contain depends on the memory size set in php.ini.

The default value is 1GB.