C# 负数和十六进制（两字节）转换

思路：

①负数转换为正数；例：-5，先转换成5（0000 0101）;第一位标识正负

②先将十进制转换为二进制通过；例：将5转换为二进制，得到结果0000 0101

③求反码；例：将上面例子求反码，得到结果：1111 1010（即0变成1,1变0）

④求补码；例：将第四步结果求补码，得到结果：1111 1011（最后一位加1）
⑤转十六进制；1111 1011转十六进制即得：FB

/// <summary>
/// 负数转十六进制
/// </summary>
/// <param name="iNumber"></param>
/// <returns></returns>
private string NegativeToHexString(int iNumber)
{
    string strResult = string.Empty;

    if (iNumber < 0)
    {
        iNumber = -iNumber;

        string strNegate = string.Empty;

        char[] binChar = Convert.ToString(iNumber, 2).PadLeft(8, '0').ToArray();

        foreach (char ch in binChar)
        {
            if (Convert.ToInt32(ch) == 48)
            {
                strNegate += "1";
            }
            else
            {
                strNegate += "0";
            }
        }

        int iComplement = Convert.ToInt32(strNegate,2) + 1;

        strResult = Convert.ToString(iComplement, 16).ToUpper();
    }

    return strResult;
}

/// <summary>

/// 十六进制转为负数
///</summary>

///<param name="strNumber"></param>

///<returns></returns>

privateint HexStringToNegative(string strNumber)
{
    int iNegate = 0;
    int iNumber = Convert.ToInt32(strNumber, 16);

    if (iNumber > 127)
    {
        int iComplement = iNumber - 1;
        string strNegate = string.Empty;

        char[] binChar = Convert.ToString(iComplement, 2).PadLeft(8, '0').ToArray();

        foreach (char ch in binChar)
        {
            if (Convert.ToInt32(ch) == 48)
            {
                strNegate += "1";
            }
            else
            {
                strNegate += "0";
            }
        }

        iNegate = - Convert.ToInt32(strNegate, 2);
    }

    return iNegate;
}