/// <summary>
/// a constructor requiring user-given positive
/// integer shift value, after the function, the state
/// is turned on.
/// precondition: parameter shift value should be positive
/// postcondition: the state changes from "off" to "on"
/// </summary>
/// <paramm name="given_shift">user-given positive integer</param>
public Driver(int given_shift)
{
this.ew = new encryptWord(given_shift);
}
/// <summary>
/// non-argument constructor function with default
/// shift as 0.
/// precondition: none
/// postcondition: no state change
/// </summary>
public Driver()
{
this.ew = new encryptWord();
}