Differentiate GET and POST methods?

GET and POST are HTTP methods for sending data between client and server.

Detailed Comparison:

GET Method Examples:

// URL: https://example.com/search.php?q=php&category=tutorial
// Accessing GET data
$searchQuery = $_GET["q"] ?? "";
$category = $_GET["category"] ?? "all";

// Validate and sanitize
$searchQuery = filter_var($searchQuery, FILTER_SANITIZE_STRING);
if (strlen($searchQuery) > 100) {
    $searchQuery = substr($searchQuery, 0, 100);
}

// Build search results
$results = searchDatabase($searchQuery, $category);

POST Method Examples:

// HTML Form
<form method="POST" action="process.php">
    <input type="text" name="username" required>
    <input type="password" name="password" required>
    <input type="submit" value="Login">
</form>

// Processing POST data
if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $username = filter_input(INPUT_POST, "username", FILTER_SANITIZE_STRING);
    $password = $_POST["password"];
    
    // Validate
    if (empty($username) || empty($password)) {
        $error = "All fields are required";
    } else {
        // Process login
        $user = authenticateUser($username, $password);
    }
}

When to Use:

• GET: Search, filtering, pagination, public data retrieval
• POST: Login, registration, file uploads, data modification