title: What does the PHP error message "Use of undefined constant login - assumed 'login"
body: <p>Before I was hosting there were no problems, after I upload them to appear 000webhost notice "Use of undefined constant login - assumed 'login' in /storage/ssd4/109/2310109/public_html/surat/login.php on line 26" </p>
  
  <pre><code>        if (isset($_POST[login])){
          $user = $_POST['user'];
          $pass = md5($_POST['pass']);
          $login=mysql_query("SELECT * FROM phpmu_user
              WHERE username='$user' AND password='$pass' AND status='Y'");
          $cocok=mysql_num_rows($login);
          $r=mysql_fetch_array($login);
  
          if ($cocok &gt; 0){
              $_SESSION[login]        = $r[id_user];
              $_SESSION[username]     = $r[username];
              $_SESSION[namalengkap]  = $r[nama_lengkap];
              $_SESSION[password]     = $r[password];
              $_SESSION[level]        = $r[level];
              $_SESSION[unit]        = $r[unit_kerja];
  
              header('location:index.php');
          }else{
              echo "&lt;script&gt;window.alert('Maaf, Anda Tidak Memiliki akses');
                      window.location=('index.php')&lt;/script&gt;";
          }
      }
  </code></pre>