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PHP code: Copy Format Clear

<?php /* Attempt to connect to MySQL database */ $link = $mysqli; // Define variables and initialize with empty values $username = $password = $confirm_password = ""; $username_err = $password_err = $confirm_password_err = ""; // Processing form data when form is submitted if($_SERVER["REQUEST_METHOD"] == "POST"){ // Validate username if(empty(trim($_POST["username"]))){ $username_err = "Please enter a username."; } elseif(!preg_match('/^[a-zA-Z0-9_]+$/', trim($_POST["username"]))){ $username_err = "Username can only contain letters, numbers, and underscores."; } else{ // Prepare a select statement $sql = "SELECT id FROM users WHERE username = ?"; if($stmt = mysqli_prepare($link, $sql)){ // Bind variables to the prepared statement as parameters mysqli_stmt_bind_param($stmt, "s", $param_username); // Set parameters $param_username = trim($_POST["username"]); // Attempt to execute the prepared statement if(mysqli_stmt_execute($stmt)){ /* store result */ mysqli_stmt_store_result($stmt); if(mysqli_stmt_num_rows($stmt) == 1){ $username_err = "This username is already taken."; } else{ $username = trim($_POST["username"]); } } else{ echo "Oops! Something went wrong. Please try again later."; } // Close statement mysqli_stmt_close($stmt); } } // Validate password if(empty(trim($_POST["password"]))){ $password_err = "Please enter a password."; } elseif(strlen(trim($_POST["password"])) < 6){ $password_err = "Password must have atleast 6 characters."; } else{ $password = trim($_POST["password"]); } // Validate confirm password if(empty(trim($_POST["confirm_password"]))){ $confirm_password_err = "Please confirm password."; } else{ $confirm_password = trim($_POST["confirm_password"]); if(empty($password_err) && ($password != $confirm_password)){ $confirm_password_err = "Password did not match."; } } // Check input errors before inserting in database if(empty($username_err) && empty($password_err) && empty($confirm_password_err)){ // Prepare an insert statement $sql = "INSERT INTO users (username, password) VALUES (?, ?)"; if($stmt = mysqli_prepare($link, $sql)){ // Bind variables to the prepared statement as parameters mysqli_stmt_bind_param($stmt, "ss", $param_username, $param_password); // Set parameters $param_username = $username; $param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash // Attempt to execute the prepared statement if(mysqli_stmt_execute($stmt)){ // Redirect to login page header("location: login.php"); } else{ echo "Oops! Something went wrong. Please try again later."; } // Close statement mysqli_stmt_close($stmt); } } // Close connection mysqli_close($link); } ?> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Sign Up</title> <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css"> <style> body{ font: 14px sans-serif; } .wrapper{ width: 360px; padding: 20px; } </style> </head> <body> <div class="wrapper"> <h2>Sign Up</h2> <p>Please fill this form to create an account.</p> <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post"> <div class="form-group"> <label>Username</label> <input type="text" name="username" class="form-control <?php echo (!empty($username_err)) ? 'is-invalid' : ''; ?>" value="<?php echo $username; ?>"> <span class="invalid-feedback"><?php echo $username_err; ?></span> </div> <div class="form-group"> <label>Password</label> <input type="password" name="password" class="form-control <?php echo (!empty($password_err)) ? 'is-invalid' : ''; ?>" value="<?php echo $password; ?>"> <span class="invalid-feedback"><?php echo $password_err; ?></span> </div> <div class="form-group"> <label>Confirm Password</label> <input type="password" name="confirm_password" class="form-control <?php echo (!empty($confirm_password_err)) ? 'is-invalid' : ''; ?>" value="<?php echo $confirm_password; ?>"> <span class="invalid-feedback"><?php echo $confirm_password_err; ?></span> </div> <div class="form-group"> <input type="submit" class="btn btn-primary" value="Submit"> <input type="reset" class="btn btn-secondary ml-2" value="Reset"> </div> <p>Already have an account? <a href="login.php">Login here</a>.</p> </form> </div> </body> </html>

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