unused options sometimes are either ignored as options or put as leftover args. Example: ./program -X would treat -X as a leftover arg if the X option has not been added, similarly, ./program -X -v would ignore -X if v was added but X was not. Users should be notified about invalid options, ideally by failing the program and printing the help message.
unused options sometimes are either ignored as options or put as leftover args. Example:
./program -Xwould treat-Xas a leftover arg if theXoption has not been added, similarly,./program -X -vwould ignore-Xifvwas added butXwas not. Users should be notified about invalid options, ideally by failing the program and printing the help message.