I'm not sure I'm reading the OP right but I think that their list of numbers is really [start,end] pairs encoded as decimals. "7.23" means the range from character 7 to character 23, which is contained in the range [7,133]. Probably needs to split the string representation into pairs (maybe in an array ref) and then use an in_range( $range, $start, $end ) sub to check.

Or something . . . </handwave>