Introduction
A question which is often asked on programming forums is - how do I convert a number to words?
Although many solutions have been posted over the years, we appear to be lacking a basic article on the subject here on C# Corner.
In this article, I'd therefore like to present a simple program which I've written to deal with this question for integers in the range of an Int32 (about plus or minus 2 billion) which I believe is the most useful case.
The program supports both the US and UK numbering systems. For example the number 620 would be expressed as follows:
Six Hundred Twenty (in the US system)
Six Hundred and Twenty (in the UK system)
Source Code
using System;
class Program
{
static void Main()
{
string input;
int number;
bool isValid;
bool isUK = false;
Console.WriteLine("\nEnter '0'
to quit the program at any time\n");
while (true)
{
Console.Write("\nUse
UK numbering y/n : ");
input = Console.ReadLine();
if (!(input.ToLower() == "y"
|| input.ToLower() == "n"))
Console.WriteLine("\n Must be 'y' or 'n', please try again\n");
else
{
if (input.ToLower() == "y")
isUK = true;
Console.WriteLine("\n");
break;
}
}
do
{
Console.Write("Enter
integer : ");
input = Console.ReadLine();
isValid = int.TryParse(input, out
number);
if (!isValid)
Console.WriteLine("\n Not an integer, please try again\n");
else
Console.WriteLine("\n {0}\n", NumberToText(number,
isUK));
}
while (!(isValid && number == 0));
Console.WriteLine("\nProgram
ended");
}
public static string
NumberToText(int number, bool isUK)
{
if (number == 0) return "Zero";
string and = isUK ? "and "
: ""; //
deals with UK or US numbering
if (number == -2147483648) return "Minus Two Billion One Hundred " + and +
"Forty Seven Million Four Hundred " + and + "Eighty Three Thousand " +
"Six Hundred " + and + "Forty
Eight";
int[] num = new int[4];
int first = 0;
int u, h, t;
System.Text.StringBuilder sb = new
System.Text.StringBuilder();
if (number < 0)
{
sb.Append("Minus ");
number = -number;
}
string[] words0 = {"",
"One ", "Two
", "Three ", "Four ", "Five
", "Six ", "Seven ", "Eight
", "Nine "};
string[] words1 = {"Ten ",
"Eleven ", "Twelve ", "Thirteen
", "Fourteen ", "Fifteen ", "Sixteen
", "Seventeen ", "Eighteen ", "Nineteen
"};
string[]
words2 = {"Twenty ", "Thirty ", "Forty
", "Fifty ", "Sixty ", "Seventy
", "Eighty ", "Ninety "};
string[] words3 = { "Thousand
", "Million ", "Billion " };
num[0] = number %
1000; //
units
num[1] = number / 1000;
num[2] = number /
1000000;
num[1] = num[1] - 1000
* num[2]; //
thousands
num[3] = number /
1000000000; //
billions
num[2] = num[2] - 1000
* num[3]; //
millions
for (int i = 3; i > 0; i--)
{
if
(num[i] != 0)
{
first = i;
break;
}
}
for (int i = first; i >= 0;
i--)
{
if (num[i] == 0) continue;
u = num[i] %
10; //
ones
t = num[i] / 10;
h = num[i] /
100; //
hundreds
t = t - 10 *
h; //
tens
if (h > 0) sb.Append(words0[h] + "Hundred ");
if (u > 0 || t > 0)
{
if (h > 0 || i < first) sb.Append(and);
if (t == 0)
sb.Append(words0[u]);
else if (t == 1)
sb.Append(words1[u]);
else
sb.Append(words2[t - 2] + words0[u]);
}
if (i != 0) sb.Append(words3[i - 1]);
}
return sb.ToString().TrimEnd();
}
}
Conclusion
It would not be difficult to extend this program to deal with larger integers, with decimal numbers or with specific currencies and I leave this as an exercise to those who need this functionality.