C# Arabic to English Code gives me error - asp.net

Question

can some one help me to rectify this error i have am using VS2010 ASP.Net C#3.0 i found this could on net but it is not working as it give me the error as show in the Screen shot. I am not able to understand the error message
Code reference from http://weblogs.asp.net/abdullaabdelhaq/archive/2009/06/27/displaying-arabic-number.aspx
CODE :
protected void Button1_Click(object sender, System.EventArgs e)
{ //Call Function
this.Label1.Text = "Arabic Number : <b>" + TranslateNumerals(this.TextBox1.Text) + "</b>";
}
public static string TranslateNumerals(string sIn)
{
System.Text.UTF8Encoding enc = new System.Text.UTF8Encoding();
System.Text.Decoder utf8Decoder = null;
utf8Decoder = enc.GetDecoder();
dynamic sTranslated = new System.Text.StringBuilder();
char[] cTransChar = new char[2];
byte[] bytes = {217,160 };
// Start Converting characters into Arabic mode.
char[] aChars = sIn.ToCharArray();
foreach (char c in aChars)
{
if (char.IsDigit(c))
{
bytes[1] = 160 + Convert.ToInt32(char.GetNumericValue(c));
utf8Decoder.GetChars(bytes, 0, 2, cTransChar, 0);
sTranslated.Append(cTransChar[0]);
}
else
{
sTranslated.Append(c);
}
}
return sTranslated.ToString();
}

Answer 1

The compiler is complaining about your request to implicitly convert the result of the integer addition (160 + Convert.ToInt32...) to a byte. This is a narrowing conversion; integers have a wider range than bytes do, and the compiler wants you to acknowledge, with an explicit cast operator, that you're aware that this could produce runtime errors.
Assuming that adding 160 actually does something useful to a character, I'd advise using something like this instead.
if (c >= '0' && c <= '9')
{
bytes[i] = (byte)((int)c + 160);
}
...which will properly produce, as the i'th value of the array bytes, a byte with a value 160 greater than the char c, if c represents an ASCII digit between 0 and 9.
Don't use the function char.IsDigit, which will return true even if c is a digit outside of the ASCII digit range. I don't run into this much, but since you're explicitly writing multilingual code, you'll want to handle that case.
I haven't reviewed the rest of the post you link to, but given these two quite obvious errors, I wouldn't put much faith in the correctness of the rest of it, frankly.

Answer 2

You could add a cast like (byte) in front of the 160.
I'm a little confused why such a large function is required to do that.
Updated answer:
Given that there are only 10 possible numerals to convert between, you can do something like this to make it slightly more readable. I think, anyway, I don't usually code in c#, and I'm on a mac right now... feel free to bash my code.
public static string TranslateNumerals(string sIn)
{
var sb = new System.Text.StringBuilder();
char[] arabic = { '٠', '١', '٢', '٣', '٤', '٥', '٦', '٧', '٨', '٩'};
foreach (char c in sIn) {
int idx;
// if it wasn't a number, just append it, otherwise convert it
if(!Integer.tryParse("" + c, idx)) {
sb.Append(c);
} else {
sb.Append(arabic[idx]);
}
}
return sb.toString();
}
// backwards array (which appears frontwards here)
{ '٩','٨','٧','٦','٥','٤','٣', '٢', '١', '٠'};