How to modify a cookie in PHP

What is a Cookie?

A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user’s computer. Each time the same computer requests a page with a browser, it will send a cookie too.

PHP cookies

PHP can be used to create cookies and retrieve cookie values. PHP provides the setcookie() function to set a cookie.

setcookie(name, value, expire, path, domain, security);

Only the name parameter is required. All other parameters are optional.

Create cookie

The following code creates a cookie named “admin” with the cookie value “Alex Williams”. The cookie will expire after 30 seconds. The “/” refers to the directory and means that the cookie is available in entire website. Otherwise, the directory can be specified accordingly.

This creates a global variable $_COOKIE. Values can be retrieved and modifications can be made using this variable. We can also use the isset() function to verify if the cookie is set:

<!DOCTYPE html>
<?php
$cookie_name = "admin";
// modified the cookie_value
$cookie_value = "Alex Williams";
// set cookie, the cookie will expire in 30 seconds
setcookie($cookie_name, $cookie_value, time() + 30, "/");
?>
<html>
<body>
<?php
if(!isset($_COOKIE[$cookie_name])) {
echo "Cookie named '" . $cookie_name . "' is not set!";
} else {
echo "Cookie '" . $cookie_name . "' is set!<br>";
echo "Value is: " . $_COOKIE[$cookie_name];
}
?>
</body>
</html>
Cookie 'user' is set!
Value is: Alex Porter

Modify a cookie value

To modify a value in a created cookie, use the setcookie() function again. Look at the code and output below to see this.

A user may been be shown the previous cookie value. In that case, just reload to see the updates.

<!DOCTYPE html>
<?php
$cookie_name = "admin";
$cookie_value = "Ross Geller";
setcookie($cookie_name, $cookie_value, time() + 30, "/");
?>
<html>
<body>
<?php
if(!isset($_COOKIE[$cookie_name])) {
echo "Cookie named '" . $cookie_name . "' is not set!";
} else {
echo "Cookie '" . $cookie_name . "' is set!<br>";
echo "Value is: " . $_COOKIE[$cookie_name];
}
?>
</body>
</html>
Cookie 'user' is set!
Value is: Alex Porter

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