So, you would rather beleive that the input is always exacctly what you expect rather than add ten characters to handle the situations where it isn't? "Expected user input" tends to not be.

In general, don't use any of the match variables without knowing the match succeeded. It doesn't matter what else is going on. Don't let yourself get into bad habits, or take shortcuts because you think the data will always be perfect.

The real answer, however, smells like use CGI;