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Creating and Retrieving Cookies

In this tutorial, we'll be focusing on an important aspect of PHP programming - working with cookies. If you're new to PHP or web development in general, you might be wondering what cookies are. Cookies are small files that are stored on a user's computer. They are designed to hold a modest amount of data specific to a particular client and website, which can be accessed either by the web server or the client computer.

Cookies are a fundamental aspect of web development, as they allow web applications to recognize users and remember important information about them. They're commonly used for session tracking, personalizing user experiences, and for remembering user preferences. In PHP, cookies can be created, modified, and retrieved very easily. Let's learn how.

Creating Cookies in PHP​

In PHP, a cookie is created with the setcookie() function. The setcookie() function must appear BEFORE the <html> tag. Here's the basic syntax:

setcookie(name, value, expire, path, domain, secure, httponly);
  • name: Specifies the name of the cookie
  • value: Specifies the value of the cookie
  • expire: Specifies when the cookie expires. The value is a UNIX timestamp.
  • path: Specifies the server path of the cookie
  • domain: Specifies the domain of the cookie
  • secure: Specifies whether the cookie should only be transmitted over a secure HTTPS connection. TRUE indicates that the cookie will only be set if a secure connection exists. FALSE is the default value.
  • httponly: If set to TRUE the cookie will be accessible only through the HTTP protocol (the cookie will not be accessible by scripting languages). This setting can help to reduce identity theft through XSS attacks.

Here is an example of creating a simple cookie:

<?php
setcookie("test_cookie", "test", time() + 3600, '/');
?>
<html>
<body>

In the above code, a cookie named "test_cookie" is set to have the value "test". It's set to expire in an hour (3600 seconds). The '/' path means the cookie is available within the entire domain.

Retrieving Cookies in PHP​

Once a cookie has been set, it can be accessed by using the $_COOKIE superglobal array. The array holds the names of all of the cookies that are currently accessible. Here is an example of how to retrieve a cookie:

<?php
if(!isset($_COOKIE["test_cookie"])) {
  echo "Cookie named 'test_cookie' is not set!";
} else {
  echo "Cookie 'test_cookie' is set!<br>";
  echo "Value is: " . $_COOKIE["test_cookie"];
}
?>

In this code, we first check whether the 'test_cookie' is set using the isset() function. If it's not set, we echo a message saying as much. If it is set, we echo a different message, and then use the $_COOKIE superglobal array to retrieve and echo the value of the 'test_cookie'.

That's it! You now know how to create and retrieve cookies in PHP. Practice creating your own cookies and retrieving them to get a handle on how they work. Remember, cookies are a vital part of most web applications, and understanding them is an important step in your journey to becoming a proficient PHP developer.