Regular Expresion String - "^([0-9]{2, 3})-([0-9]{7})$"
- ^ and $: matches at the very start and very end of the subject string;
- "([0-9]{2, 3})": matches the area code of an phone number , and is enclosed in brackets so that this section can be used in the replacement of the pattern ($1);
- "-": matches hyphen;
- "([0-9]{7})": matches 7-digit phone number, and is also enclosed in brackets so that this section can be used in the replacement of the pattern ($2);
Replacement String - "($1)$2"
- "$1": references to the fist catpure above, that is the area code;
- "$2": references to the second catpure above, that is the phone number;