Phone Number
Welcome to Phone Number on Exercism's Dart Track.
If you need help running the tests or submitting your code, check out HELP.md.
Instructions
Clean up user-entered phone numbers so that they can be sent SMS messages.
The North American Numbering Plan (NANP) is a telephone numbering system used by many countries in North America like the United States, Canada or Bermuda.
All NANP-countries share the same international country code: 1.
NANP numbers are ten-digit numbers consisting of a three-digit Numbering Plan Area code, commonly known as area code, followed by a seven-digit local number. The first three digits of the local number represent the exchange code, followed by the unique four-digit number which is the subscriber number.
The format is usually represented as
(NXX)-NXX-XXXX
where N is any digit from 2 through 9 and X is any digit from 0 through 9.
Your task is to clean up differently formatted telephone numbers by removing punctuation and the country code (1) if present.
For example, the inputs
+1 (613)-995-0253613-995-02531 613 995 0253613.995.0253
should all produce the output
6139950253
Note: As this exercise only deals with telephone numbers used in NANP-countries, only 1 is considered a valid country code.
A function with a return type can only return data of that type and null.
However the function caller is only expecting one data type.
Example:
String hello(int a){
if ( a == 0){
return "a";
} else {
return null;
}
}
To make it more clear that this function can also return null or more data types, use dynamic.
dynamic hello(int a){
if ( a == 0){
return "a";
} else {
return null;
}
}
## Source
### Created by
- @devkabiir
### Contributed to by
- @kytrinyx
- @Stargator
### Based on
Exercise by the JumpstartLab team for students at The Turing School of Software and Design. - https://turing.edu