C++ Program to Convert Numbers Into Their Words Equivalent

#include <iostream>
#include <string.h>
#include <string>
using namespace std;
/*
    The program converts a number to its word equivalent.
    For example, 1 One ,2 -> two ,3 -> three .............
*/
unsigned long long int Denominations[] = {1000000000000000000,1000000000000000,
                1000000000000,1000000000,1000000
                                          ,1000,100,1
                                         };
const int No_Of_Denums = sizeof(Denominations)/sizeof(long long int);
char Ones[][20] = {"zero","one ","two ","three ","four ","five ","six ",
                "seven ","eight ","nine "
                  };
char Tens[][20] = {"twenty ","thirty ","forty ","fifty ","sixty ",
                "seventy ","eighty ","ninety "
                  };
char Scale[][20] = {"hexillion ","quintillion ","quadrillion ","trillion ","billion ","million ",
                "thousand ","hundred ",""
                   };
char Teens[][20] = {"ten ","eleven ","twelve ","thirteen ",
                "fourteen ","fifteen ","sixteen ","seventeen ","eighteen "
                    ,"nineteen "
                   };
string UnderHundred(int n)
{
                // n is known to be under 1000. Hence first split up it into 3 numbers
                int n1,n2,n3;
    n1=n%10;
    n/=10;
    n2=n%10;
    n/=10;
    n3=n%10;
    string s="";
                if (n3!=0)
    {
        s+=Ones[n3];
        s+="hundred ";
    }
                if (n2!=0)
    {
                if (n2==1)      //Different construction for Teens, ten inclusive
        {
            s+=Teens[n1];
                return s;
        }
        s+=Tens[n2-2];
        s.replace(s.length()-1,1,"-");
    }
    s+=Ones[n1];
                return s;
}
string Words(unsigned long long int n)
{
                int DenumCount[No_Of_Denums] = {0};
                int DenumPointer=0;
                while (true)
    {
                if (n < Denominations[DenumPointer])
        {
            DenumPointer++;
                if (DenumPointer>=No_Of_Denums)
            {
                break;
            }
                continue;
        }
        DenumCount[DenumPointer]++;
        n-=Denominations[DenumPointer];
    }
    string s="";
                //Now create a string on the basis of those values
                for (int i=0; i<No_Of_Denums; i++)
    {
                if (DenumCount[i]==0) continue;
        s+=UnderHundred(DenumCount[i]);
        s+=Scale[i];
    }
                //Convert to first letter to ucase
    s[0] = toupper(s[0]);
                return s;
}
int main()
{
                unsigned long long int i;
                unsigned long long int Limit = 0xFFFFFFFFFFFFFFFF;
    cout << "Print the number you wish to convert. (0) to exit\n";
    cout << Limit <<" is the limit.\n\n";
                while(true)
    {
        cout << "Enter a number to find the word spell\n" << endl;
        cin >> i;
                if (!i) break;
        string s = Words(i);
        cout << Words(i) << endl;
    }
                return 0;
}
/*
OUTPUT:
Print the number you wish to convert. (0) to exit
18446744073709551615 is the limit.
Enter a number to find the word spell
64
Sixty-four hundred
Enter a number to find the word spell
*/