Trouble with strings and arrays

Question

My goal is to make a program that inputs a phone number and outputs it in a standard format. It skips over any non-number characters, will output if there are not enough digits, and will also skip over any digits after the first ten digits. My raptor worked without a hitch, but it's been difficult to translate it to C++.

I am using Microsoft Visual Studio. The problem is it is not running. If I put in anything more then one number in, I receive a fail error.

I am having some difficulty running this code. Any and all help and advice would be greatly appreciated.

#include <iostream>
#include <string>
using namespace std;

void format(char outArray[], string inNumber)
{
    outArray[0] = '(';
    outArray[4] = ')';
    outArray[5] = ' ';
    outArray[9] = '-';

    outArray[1] = inNumber[0];
    outArray[2] = inNumber[1];
    outArray[3] = inNumber[2];
    outArray[6] = inNumber[3];
    outArray[7] = inNumber[4];
    outArray[8] = inNumber[5];
    outArray[10] = inNumber[6];
    outArray[11] = inNumber[7];
    outArray[12] = inNumber[8];
    outArray[13] = inNumber[9];
}

int main()
{
    string phone, inNumber;
    cout << "Please enter a phone number: ";
    cin >> phone;
    int index = 0;
    int num = 0;
    char outArray[14];

    for (index; phone[index] >= '0' && phone[index] <= '9'; index++)
    {
        inNumber[num] = phone[index];
        num++;
    }

    if (inNumber.size() > 10)
    {
        format(outArray, inNumber);

        cout << "The properly formatted number is: ";
        cout << outArray;
    }
    else {
        cout << "Input must contain at least 10 digits." << endl;
    }

    system("pause");
    return 0;
}

Answer 1

A few things to note:

• Use std::string instead array of char array.

• You do not need to check charters using a for loop unless you are not sure about the input(phone). However, if that's the case, use std::getline() to get the input and parse as follows using a range-based for loop.

• You can use std::isdigit to check the character is a digit.

  My goal is to make a program that inputs a phone number and outputs it in a standard format. It skips over any non-number characters, will output if there are not enough digits, and will also skip over any digits after the first ten digits.

• That means the number should have a minimum length of 10. Then the if statement should be if (inNumber.size() >= 10)

• Need a pass by ref call in the function format(), since you want to change the content of outArray. Additionally, inNumber could be a const ref, since we do not change this string.

Updated code: (See a sample code online)

#include <iostream>
#include <string>
#include <cstddef>   // std::isdigit, std::size_t

void format(std::string& outArray, const std::string& inNumber) /* noexcept */
{
   for (std::size_t index = 0; index < 10; ++index)
   {
      if (index == 0) outArray += '(';
      else if (index == 3) outArray += ") ";
      else if (index == 6) outArray += '-';
      outArray += inNumber[index];
   }
}

int main()
{
   std::string phone;
   std::cout << "Please enter a phone number: ";
   std::getline(std::cin, phone);

   std::string inNumber;

   for (char letter : phone)
      if (std::isdigit(static_cast<unsigned char>(letter))) // check the letter == digits
         inNumber += letter;


   if (inNumber.size() >= 10)
   {
      std::string outArray;
      format(outArray, inNumber);
      std::cout << "The properly formatted number is: ";
      std::cout << outArray;
   }
   else {
      std::cout << "Input must contain at least 10 digits." << std::endl;
   }
   return 0;
}

Answer 2

 inNumber[num] = phone[index]; //undefined behavior.

You cannot subscript inNumber now, since its capacity is 0, thus it can not store or access any element here.

You may need to use string's constructor whose parameter has a size_t type or string::reserve or string::resize.

And I'm happy to see cppreference get more complete now, learn to use it: http://en.cppreference.com/w/cpp/string/basic_string

BTW, this function won't do anything you want to:

void format(char outArray[], string inNumber)

maybe you'd like to have an signature like this?

void format(char outArray[], string& inNumber)