function checkLogin()

function checkLogin() {
  // originally header.php

  // if user is logged in
  if(isset($_SESSION['username'])) {
    $username = $_SESSION['username'];

    // run query to get users avatar
    $getAvatar = dbConnect()->prepare("SELECT * FROM users WHERE username = :username");
    $getAvatar->bindParam(':username', $username);
    // execute query
    $getAvatar->execute();
    // set each column as row
    $row = $getAvatar->fetch(PDO::FETCH_ASSOC);
    // set $avatar as users set avatar
    $avatar = $row['avatar'];

    // echo avatar, certain nav elements!!
    echo '
    <div class="navbar-right">
       <!-- icons -->
       <img src="http://i.imgur.com/HD6W7XJ.png" class="icon-search" alt="search-icon" />

       <span class="icon-bars-button">
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
       </span>

    ';

    // if user doesn't have avatar set:
    if (empty($avatar)) {

      // echo default avatar...
      echo '<img src="http://i.imgur.com/QFxs0nX.png" class="user_avatar" alt="default avatar" />';

    // if user has set an avatar:
    } else {

      // echo set avatar...
      echo '
      <!-- user avatar -->
      <img src="data:image/jpeg;base64,' . base64_encode($avatar) . '" class="user_avatar" alt="' .$username. ' avatar" />
      ';

    }

    echo '
    </div>';

  // if user is not logged in ..
    } else {

  // echo sign-up and log-in btns
    echo '
    <div class="navbar-right">
       <!-- sign up / log in buttons -->
       <a href="register.php"><button type="button" class="sign-up">Sign Up</button></a>
       <a href="login.php"><button type="button" class="log-in">Log In</button></a>

       <!-- icons -->
       <img src="http://i.imgur.com/HD6W7XJ.png" class="icon-search" alt="search-icon" />

       <span class="icon-bars-button">
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
          <span class="icon-bar"></span>
       </span>
    </div>
    ';
  }
  // check for errors logging in...
  //checkLoginErrors();
}