C#实现计算器，支持括号运算

有些面试题要实现一个计算器。自己尝试了一下。若有问题请留言说明。我好及时纠正。

public class CalcHelper    {        public double CalcBrackets(ref string str)        {            char[] array = str.ToArray();            string tex = str;            int count = 1;            int endIndex = 0;            for(int i=1;i<array.Length;i++)            {                if (array[i] == '(')                    count++;                if (array[i] == ')')                    count--;                if (count == 0)                { endIndex = i;break; }            }            tex = tex.Substring(1,endIndex-1);            str = str.Substring(endIndex+1);            var result = StrCalc(0, ref tex);            return result;        }        public double GetANumber(ref string str)        {            char first = str.First();            if (first == '(')            {                double result = 0;                result = CalcBrackets(ref str);                return result;            }            char[] array = str.ToArray();            int end = 0;            int point = -1;            for (int i = 0; i < array.Length; i++)            {                if (array[i] < 0x30 && array[i] > 0x39 && array[i] != 0x2E)                {                    end = i;                    break;                }                if (array[i] == 0x2E)                {                    point = i;                }            }            double Value = 0;            Value += array[0]-0x30;            if(point>=0)            {                for (int i = 1; i < point; i++)                    Value = Value * 10 + (array[i]-0x30);                double except = 10.0;                for(int i=point+1;i<end;i++)                {                    Value += (array[i]-0x30) / except;                    except *= 10;                }            }            else            {                for (int i = 1; i < end; i++)                    Value = Value * 10 + (array[i]-0x30);            }            str = str.Substring(++end);            return Value;        }        public double StrCalc(double A,ref string str)        {            if (str.Length == 0) return A;            char first = str.First();              double result = 0;            if (first >= 0x30 && first <= 0x39)            {                result = GetANumber(ref str);                result = StrCalc(result, ref str);            }            else if (first == '+')            {                str = str.Substring(1);                result = A + StrCalc(0, ref str);            }            else if (first == '-')            {                str = str.Substring(1);                result = A - StrCalc(0, ref str);            }            else if (first=='(')            {               result= CalcBrackets(ref str);               result = StrCalc(result, ref str);            }            else if (first == '*')            {                str = str.Substring(1);                result = A * GetANumber(ref str);            }            else if (first == '/')            {                str = str.Substring(1);                result = A / GetANumber(ref str);            }            return result;        }    }

调用方法:

CalcHelper calc = new CalcHelper();            string cmd = "1+1+1+1+3*3+1+2-((3*4)+5)*(6-7)+9/(3-1)";            var result = calc.StrCalc(0, ref cmd);            while(cmd.Length!=0)                result=calc.StrCalc(result, ref cmd);