测绘取位函数

 static public double GetNumber(double xIn,int decimalNumber)
        {
            //该函数主要实现数值的测绘进位问题
            //xIn:读入的数值
            //decimalNumber：保留的小数位数
            //返回值：双精度
            //by zzh_my@163.com
            //language c#
            //creat at 2010-12
            //last modify at 2010-12
            int a = decimalNumber;//保留的小数个数
            string xStr = xIn.ToString();
            string xStrOut = "";
            //获取xStr长度lAll，
            int lAll = xStr.Length;
            //（3）小数点位置lDot，
            int lDot = xStr.IndexOf(".");
            //未找到小数点则返回-1
            if (lDot > 0)
            {
                //1、则小数部分长度lLit=lAll-lDot
                int lLit = lAll - lDot - 1;
                //2、如果lLit=a,则原样输出
                if (lLit == a)
                {
                    xStrOut = xStr;
                }
                //3、如果lLit
                if (lLit < a)
                {
                    xStrOut = xStr.PadRight(lDot + a + 1, '0');
                }
                //4、如果lLit>a,则考虑
                if (lLit > a)
                {
                    //小数点后第a+1位 a_1Deal
                    int a_1Deal = lDot + a + 1;
                    //一、如果char[a_1Deal]>5,则char[lDot+a]+1;
                    if (Convert.ToInt16(xStr.Substring(a_1Deal, 1)) > 5)
                    {
                        xStrOut = xStr.Substring(0, lDot + a) + Convert.ToString(Convert.ToInt16(xStr.Substring(a_1Deal - 1, 1)) + 1);
                    }
                    //二、如果char[a_1Deal]<5,则截断xStr至小数点后a位
                    if (Convert.ToInt16(xStr.Substring(a_1Deal, 1)) < 5)
                    {
                        xStrOut = xStr.Substring(0, a_1Deal);
                    }
                    //三、如果char[a_1Deal]==5，则
                    if (Convert.ToInt16(xStr.Substring(a_1Deal, 1)) == 5)
                    {
                        //  //（一）、如果第小数后第a-1位，为偶数，则同 二
                        if (Convert.ToInt16(xStr.Substring(a_1Deal - 1, 1)) % 2 == 0)
                        {
                            xStrOut = xStr.Substring(0, a_1Deal);
                        }
                        // （二）、如果第小数后第a-1位，为奇数，则同 一
                        if (Convert.ToInt16(xStr.Substring(a_1Deal - 1, 1)) % 2 != 0)
                        {
                            xStrOut = xStr.Substring(0, lDot + a) + Convert.ToString(Convert.ToInt16(xStr.Substring(a_1Deal - 1, 1)) + 1);
                        }
                    }

                }
            }
            else
            {
                xStr = xStr + ".";
                xStrOut = xStr.PadRight(lAll + 1 + a, '0');
            }
            return Convert.ToDouble(xStrOut);
        }