Lucene.Net.QueryParsers.QueryParser.HexToInt C# (CSharp) Method

        private static int HexToInt(char c)
        {
            if ('0' <= c && c <= '9')
            {
                return c - '0';
            }
            else if ('a' <= c && c <= 'f')
            {
                return c - 'a' + 10;
            }
            else if ('A' <= c && c <= 'F')
            {
                return c - 'A' + 10;
            }
            else
            {
                throw new ParseException("None-hex character in unicode escape sequence: " + c);
            }
        }