转帖：c#任意进制转换(2-36进制之间的转换)

转帖：c#任意进制转换(2-36进制之间的转换)

{     private static char[] rDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };

public class AnyRadixConvert

    /// <summary>
    /// 将指定基数的数字的 System.String 表示形式转换为等效的 64 位有符号整数。
    /// </summary>
    /// <param name="value">包含数字的 System.String。</param>
    /// <param name="fromBase">value 中数字的基数，它必须是[2,36]</param>
    /// <returns>等效于 value 中的数字的 64 位有符号整数。- 或 - 如果 value 为 null，则为零。</returns>
    private long x2h(string value, int fromBase)
    {
        value = value.Trim();
        if (string.IsNullOrEmpty(value))
        {
            return 0L;
        }

        string sDigits = new string(rDigits, 0, fromBase);
        long result = 0;
        //value = reverse(value).ToUpper(); 1
        value = value.ToUpper();// 2
        for (int i = 0; i < value.Length; i++)
        {
            if (!sDigits.Contains(value[i].ToString()))
            {
                throw new ArgumentException(string.Format("The argument \"{0}\" is not in {1} system.", value[i], fromBase));
            }
            else
            {
                try
                {
                    //result += (long)Math.Pow(fromBase, i) * getcharindex(rDigits, value[i]); 1
                    result += (long)Math.Pow(fromBase, i) * getcharindex(rDigits, value[value.Length - i - 1]);//   2
                }
                catch
                {
                    throw new OverflowException("运算溢出.");
                }
            }
        }

        return result;
    }

    private int getcharindex(char[] arr, char value)
    {
        for (int i = 0; i < arr.Length; i++)
        {
            if (arr[i] == value)
            {
                return i;
            }
        }
        return 0;
    }

    //long转化为toBase进制
    private string h2x(long value, int toBase)
    {
        int digitIndex = 0;
        long longPositive = Math.Abs(value);
        int radix = toBase;
        char[] outDigits = new char[63];

        for (digitIndex = 0; digitIndex <= 64; digitIndex++)
        {
            if (longPositive == 0) { break; }

            outDigits[outDigits.Length - digitIndex - 1] =
                rDigits[longPositive % radix];
            longPositive /= radix;
        }

        return new string(outDigits, outDigits.Length - digitIndex, digitIndex);
    }

    //任意进制转换,将fromBase进制表示的value转换为toBase进制
    public string X2X(string value, int fromBase, int toBase)
    {
        if (string.IsNullOrEmpty(value.Trim()))
        {
            return string.Empty;
        }

        if (fromBase < 2 || fromBase > 36)
        {
            throw new ArgumentException(String.Format("The fromBase radix \"{0}\" is not in the range 2..36.", fromBase));
        }

        if (toBase < 2 || toBase > 36)
        {
            throw new ArgumentException(String.Format("The toBase radix \"{0}\" is not in the range 2..36.", toBase));
        }

        long m = x2h(value, fromBase);
        string r = h2x(m, toBase);
        return r;
    }
}