Number To Words

NumberToWords.cpp

#include <map>
#include <string>
#include <vector>
#include <iostream>
#include "ConsoleApplication10.h"

std::map<const int, const std::string> Numbers =
{
	{1, "one" },		{2, "two"},		{3, "three"},		{4, "four"},		{5, "five"},	
	{6, "six"},		{7, "seven"},		{8, "eight"},		{9, "nine"},		{10, "ten"},
	{11, "eleven"},		{12, "twelve"},		{13, "thirteen"},	{14, "fourteen"},	{15, "fifteen"},
	{16, "sixteen"},	{17, "seventeen"},	{18, "eighteen"},	{19, "nineteen"},	{20, "twenty"},
	{30, "thirty"},		{40, "forty"},		{50, "fifty"},		{60, "sixty"},		{70, "seventy"},
	{80, "eighty"},		{90, "ninety"}		
};

std::string ParseGroup(std::string Val, int group)
{
	const std::vector<std::string> vals = { "thousand", "million", "billion" };
	std::string retVal;
	bool teens = false;

	switch (Val.length())
	{
	case 3:
		if (Val[0] != '0')
		{
			retVal = Numbers[Val[0] - '0'];
			retVal += " hundred ";
		}
		Val.erase(0, 1);
	case 2:
		if (Val[0] != '0')
		{
			if (Val[0] == '1')
			{

				std::string teen = Val.substr(0, 2);
				retVal += Numbers[std::stoi(teen)];
				teens = true;
				retVal += " ";
				if (group >= 0)
				{
					retVal += vals[group];
					retVal += " ";
				}
				return retVal;
			}
			else
			{
				retVal += Numbers[(Val[0] - '0') * 10];
			}
		}
		Val.erase(0, 1);
	case 1:
		if (!teens)
		{
			retVal += Numbers[Val[0] - '0'];
			retVal += " ";
			if (group >= 0 && retVal != " ")
			{
				retVal += vals[group];
				retVal += " ";
			}
		}
	}

	return retVal;
}

int main()
{
	std::string result;
	long long int Value = 999888777015;
	std::string strVal = std::to_string(Value);
	if (strVal.length() > 12)
	{
		std::cout << "Value is too long. Can't be more than 999,999,999,999\n";
		return -1;
	}

	int groups = (strVal.length() / 3) + (strVal.length() % 3 ? 1 : 0);
	int InitLen = 3;
	switch (strVal.length() % 3)
	{
	case 1:
		InitLen = 1;
		break;
	case 2:
		InitLen = 2;
		break;
	}

	for (int i = 0, group = 2; i < groups; i++, group--)
	{
		result += ParseGroup(strVal.substr(0, InitLen), group);
		strVal.erase(0, InitLen);
		InitLen = 3;
	}

	std::cout << Value << " in words is:\n" << result << "\n\n\n";
	return 0;
}