digits.cpp

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

// illustrates loops, convert a number to a string of English digits
// i.e., 1346 -> one three four six
// Owen Astrachan, 6/8/95

string DigitToString(int num);
string StringOut(long int number);

int main()
{
    long number;
    
    cout << "enter an integer: ";
    cin >> number;
    cout << StringOut(number) << endl;
    
    return 0;
}

string DigitToString(int num)
// precondition: 0 <= num < 10
// postcondition: returns english equivalent, e.g., 1->one,...9->nine     
{
    if (0 == num)       return "zero";
    else if (1 == num)  return "one";
    else if (2 == num)  return "two";
    else if (3 == num)  return "three";
    else if (4 == num)  return "four";
    else if (5 == num)  return "five";
    else if (6 == num)  return "six";
    else if (7 == num)  return "seven";
    else if (8 == num)  return "eight";
    else if (9 == num)  return "nine";
    else return "?";
}

string StringOut(long number)
// precondition: 0 < number
// postcondition: returns string formed from digits written in English     
//                e.g., 123 -> "one two three"
{
    string s = "";
    int digit;
    while (number != 0)
    {   digit = number % 10;
        s = DigitToString(digit) + " " + s;
        number /= 10;
    }
    return s;
}