wt_10_form_validation

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Form Validation Using Regular Expressions</title>
</head>

<body>
    <h2>Registration Form</h2>
    <form method="POST" action="">
        <label for="email">Email:</label><br>
        <input type="email" id="email" name="email"
            value="<?php echo isset($_POST['email']) ? htmlspecialchars($_POST['email']) : ''; ?>" required><br><br>
        <label for="username">Username (5-15 characters, letters, and numbers only):</label><br>
        <input type="text" id="username" name="username"
            value="<?php echo isset($_POST['username']) ? htmlspecialchars($_POST['username']) : ''; ?>"
            required><br><br>
        <label for="password">Password (min 8 characters, at least one letter and one number):</label><br>
        <input type="password" id="password" name="password"
            value="<?php echo isset($_POST['password']) ? htmlspecialchars($_POST['password']) : ''; ?>"
            required><br><br>
        <input type="submit" name="submit" value="Submit">
    </form>
    <?php
    // Run the validation logic only after the form is submitted
    if ($_SERVER["REQUEST_METHOD"] == "POST") {
        // Get user inputs from form submission
        $email = $_POST['email'];
        $username = $_POST['username'];
        $password = $_POST['password'];
        // Function to validate email using regex
        function validateEmail($email)
        {
            return preg_match("/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/", $email);
        }
        // Function to validate username using regex
        function validateUsername($username)
        {
            return preg_match("/^[a-zA-Z0-9]{5,15}$/", $username);
        }
        // Function to validate password using regex
        function validatePassword($password)
        {
            return preg_match("/^(?=.*[A-Za-z])(?=.*\d)[A-Za-z\d]{8,}$/", $password);
        }// Validate the inputs
        $isEmailValid = validateEmail($email);
        $isUsernameValid = validateUsername($username);
        $isPasswordValid = validatePassword($password);
        // Output validation results after form submission
        echo "<h3>Validation Results:</h3>";
        echo "Email validation: " . ($isEmailValid ? "Valid" : "Invalid") . "<br>";
        echo "Username validation: " . ($isUsernameValid ? "Valid" : "Invalid") . "<br>";
        echo "Password validation: " . ($isPasswordValid ? "Valid" : "Invalid") . "<br>";
    }
    ?>
</body>

</html>