All the sources codes "But why ?"page 41

public boolean isNegative(int i) {
    String s = Integer.parseInt(i);
    return s.startsWith("-");
}

int length = 0;
for(int idx = 0; idx < a.length; i++) {
     length++;
}
System.out.println("length is : " + length);

          } else {
            $errmsg='An unknown error occured.';
          }
          $errmsg='The passwords you entered do not match';
        } else {
          $errmsg='Password has to be at least 8 characters long.';
        }
      } else {
        $errmsg='The email you entered is already in our database.';
      }
    } else {
      $errmsg='Please enter your email address.';
    }
  } else {
    $errmsg='Please enter your first name and your last name.';
  }
} else {
(...)