static BigInteger ToBigInteger(string value, int @base)
{
const string HEX = "0123456789ABCDEF";
if (@base < 1 || @base > HEX.Length)
{
throw new ArgumentException("Base is out of range.");
}
BigInteger bi = BigInteger.Zero;
foreach (char c in value)
{
char c2 = Char.ToUpper(c);
int idx = HEX.IndexOf(c2);
if (idx == -1 || idx >= @base)
{
throw new ArgumentOutOfRangeException("Illegal character encountered.");
}
bi = bi * @base + idx;
}
return(bi);
}
