while (<>) {
        # Only require a non-null first capture
        if (/(\w\w)(\w\w)?(\w\w)?(\w\w)?/) {
            # Do something
        }
    }

##</code><code>##

    if (/(\s*\w\w)(\s+\w\w)?(\s+\w\w)?(\s+\w\w)?/) {
        # Do something
    }