signup.php

<!DOCTYPE html>
<html>
  <head>
    <title>Mismatch - Sign Up</title>
    <meta charset="utf-8">
  </head>
  <body>
<?php
  require_once('appvars.php');
  require_once('connectvars.php');

  // Connect to the database
  $dbc = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);

  if(isset($_POST['submit'])
  {
    // Grab the profile data from POST
    $username = $_POST['username']);
    $password1 = $_POST['password1']);
    $password2 = $_POST['password2']);

    if(!empty($username) && !empty($password1) && !empty($password2) &&
    ($password1 == $password2) )
    {
      // Make sure someone isn't already registered with this username

      $query = "SELECT * FROM mismatch_user WHERE username = '$username'";

      $data = mysqli_query($dbc, $query);
      if(mysqli_num_rows($data) == 0)
      {
        // The username is unique, so insert the data into the database
        $query = "INSERT INTO mismatch_user (username, password, date) VALUES" .
                 "('$username', SHA('$password1'), NOW())";
        mysqli_query($dbc, $query);

        // Confirm success with the user
        echo '<p>Your new account has been successfully created. You\'re ready to log in and ' .
             '<a href="editprofile.php">edit your profile</a>.</p>';
        mysqli_close($dbc);
        exit();
      }
      else
      {
         // An account already exists for this username, so display an error message
         echo '<p class="error">An account already exists for this username. ' .
              'Please use a different address.</p>';
         $username = "";
      }
    }
    else
    {
       echo '<p class="error">You must enter all of the sign-up data, ' .
             'including the desired password twice.</p>';
    }
  }
?>

    <p>Please enter you username and desired password to sign up to Mismatch.</p>
    <form method="post" action="<?php echo $_SERVER['PHP_SELF']?>">
      <fieldset>
        <legend>Registration Info</legend>
        <label for="username">Username:</label>
        <input type="text" id="username" name="username" value="<?php if(!empty($username)) echo $username;?>"><br>
        <label for="password1">Password:</label>
        <input type="password" id="password1" name="password1" value="<?php if(!empty($password1)) echo $password1;?>"><br>
        <label for="password2">Password (retype):</label>
        <input type="password" id="password2" name="password2"><br>
      </fieldset>
    </form>
  </body>
</html>