Daily Challenge #9 - What's Your Number?

I think this challenge description is very country specific, as every country has a different way of formatting these.

I agree with the other commentors that we need an example in the post to make it easier to understand! Especially with all the different ways telephone numbers are handled country to country.

Luckily the linked Codewars page has an example!

createPhoneNumber([1, 2, 3, 4, 5, 6, 7, 8, 9, 0]) // => returns "(123) 456-7890"

JavaScript

I assumed the US phone number format that is (XXX) XXX-XXXX

const formatNumber = numbers => {

  let phoneNumber = "";

  // prerequisites:
  //   - input must be an array
  //   - with 10 elements
  //   - each element will be a single digit number
  if (
    Array.isArray(numbers) &&
    numbers.length === 10 &&
    numbers.every(n => n > -1 && n < 10)
  ) {
    // break the phone number into parts and generate the formmated string
    const areaCode = numbers.slice(0,3).join('');
    const firstPart = numbers.slice(3,6).join('');
    const secondPart = numbers.slice(6).join('');
    phoneNumber = `(${areaCode}) ${firstPart}-${secondPart}`;
  }

  return phoneNumber;
}

Live demo on CodePen (with an alternative version in one line).

Nim

import strutils
from sequtils import map

const phone_number = @[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]

proc createPhoneNumber(numbers: seq[int]): string =
  if len(numbers) < 10:
    raise newException(ValueError, "invalid length provided to createPhoneNumber(), requires 10 digits")

  return "($#$#$#) $#$#$#-$#$#$#$#" % numbers.map(proc (p: int): string = intToStr(p))



# Run
echo createPhoneNumber(phone_number)

Could you provide an example? The length and format tends to differ in different countries.
In Costa Rice, for example, it might be 8 or 11 numbers long; as in 8765-4321, or, with the country code, (+506) 8765-4321. Either way it’s not 10 characters.
Thanks!

That's not the first time a challenge is not well explained. You need to grab the whole problem description here to let people give possible solutions. I like these challenges but need a good and clear description of the problem, why don't connect to codewars directly?

#! /usr/bin/perl
use warnings;
use strict;

sub phone_num {
    local $" = "";
    "(@_[0 .. 2]) @_[3..5]-@_[6..9]"
}

use Test::More tests => 1;
is phone_num(0 .. 9), '(012) 345-6789';

The special variable $" is used to separate arrays interpolated in double quotes. By default, it contains a space, but we need the numbers to be adjacent, so we set it locally (i.e. in a dynamic scope) to an empty string.

Another possible short solution is

sub phone_num {
    "(012) 345-6789" =~ s/(\d)/$_[$1]/gr
}

The substitution replaces each digit in the template string with the corresponding element of the @_ array which keeps the list of the subroutine arguments. /g means "global", it's needed to replace all the digits, not just the first one. The /r means "return" - normally, a substitution changes the bound left-hand side value, but with /r, it just returns the value.

python3

#!/usr/bin/env python3


def createPhoneNumber(array_of_integers):
    return "(%s%s%s) %s%s%s-%s%s%s%s" % tuple(array_of_integers)


if __name__ == '__main__':
    print(createPhoneNumber([1, 2, 3, 4, 5, 6, 7, 8, 9, 0]))

Erlang: (in the REPL)

Num = [8,0,0,5,5,5,1,2,1,2].
io:format("(~B~B~B) ~B~B~B-~B~B~B~B~n", Num).
(800) 555-1212
ok

Or you can use io_lib:format and assign the result to a variable instead.

Checking for valid input is fairly trivial, but the Erlang convention is to assume that something this far into the system is okay, and correct for the error by dying and letting the supervisor deal with it.

Python

var = input("Enter 10 integers: ")
var = list(var)

if len(var) != 10:
        print("Invalid Entry")
else:
        print('(',var[0],var[1],var[2],') ',var[3],var[4],var[5],'-',var[6],var[7],var[8],var[9], sep='')

anyone's skin crawling?