PHP $_COOKIE

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 the cookie too. With PHP, you can both create and retrieve cookie values.

1. Setting a Cookie

A cookie is created with the setcookie() function. This function must appear before any HTML tags.

Syntax: setcookie(name, value, expire, path, domain, secure, httponly)

<?php
    $cookie_name = "user";
    $cookie_value = "John Doe";
    // Set cookie to expire in 30 days (86400 * 30)
    setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/"); 
?>

2. Retrieving a Cookie Value

To check if a cookie is set and get its value, use the $_COOKIE superglobal array. Use isset() to avoid errors if the cookie doesn't exist.

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

3. Modifying and Deleting

To modify a cookie, just set the cookie again using the setcookie() function with the same name. To **delete** a cookie, use the setcookie() function with an expiration date in the past.

<?php
    // Delete cookie by setting expiry to 1 hour ago
    setcookie("user", "", time() - 3600, "/");
?>

Key Takeaways

• Cookies store data on the client side (browser).
• Use setcookie() to create, modify, and delete data.
• Always provide a path (usually "/") to make cookies available across your site.
• Cookies are great for non-sensitive preferences like theme (dark/light mode).
• Retrieve values using the $_COOKIE array.