栈的应用-四则表达式(C#代码实现)

->概念
中缀表达式 9+(3-1)*3+10/2
转换步骤
9 +
9 + (
9 3 + ( -
9 3 1 + ( - )
9 3 1 - +
9 3 1 - + *
9 3 1 - 3 + * +
9 3 1 - 3 * + +
9 3 1 - 3 * + 10 +
9 3 1 - 3 * + 10 + /
9 3 1 - 3 * + 10 2 +/
9 3 1 - 3 * + 10 2 / +

后缀表达式 9 3 1 - 3 * + 10 2 / +
9 3 1 -
9 2 3
9 2 3 *
9 6 +
15 10 2 /
15 5 +
20

转换规则
从左到右遍历中缀表达式的每个数字和符号,若是数字就输出,即成为
后缀表达式的一部分;若是符号,则判断其与栈顶符号的优先级别,是
右括号或优先级低于栈顶符号(乘除优先加减)则栈顶元素依次出栈并
输出,并将当前符号进栈,一直到最终输出后缀表达式为止

        /// <summary>
        /// 定义级别
        /// </summary>
        static my[] mylist = {new my{i=0,deouce=")"},
                              new my{i=1,deouce="+"},
                             new my{i=1,deouce="-"},
                             new my{i=2,deouce="*"},
                             new my{i=2,deouce="/"},
                             new my{i=3,deouce="("}
                             };
        static void Main(string[] args)
        {
            string s = "(1000*1000-10)+89*22";
            List<string> ds = HouZui(getStr(ggg(s)));
            Console.WriteLine(Reuslt(ds));
            Console.Read();
        }
        /// <summary>
        /// 计算结果的
        /// </summary>
        /// <param name="Tstr">后缀表达式</param>
        /// <returns>结果</returns>
        private static double Reuslt(List<string> Tstr)
        {
            Stack<double> stack = new Stack<double>();
            foreach (var item in Tstr)
            {
                if (isNumber(item))
                {
                    stack.Push(double.Parse(item));
                }
                else
                {
                    double d1 = stack.Pop();
                    double d2 = stack.Pop();
                    stack.Push(GetResult(item, d2, d1));
                }
            }
            return stack.Pop();
        }
//根据中缀表达式转换成后缀表达式
        private static List<string> HouZui(string[] ds)
        {
            List<string> Ts = new List<string>();
            Stack<string> stack = new Stack<string>();
            for (int i = 0; i < ds.Length; i++)
            {
                string stemp = ds[i];
                if (isNumber(stemp))//是数字就直接添加到字符串集合中
                {
                    Ts.Add(stemp);
                }
                else//是符号就判断
                {
                    string strtemp = " ";
                    try
                    {
                        strtemp = stack.Peek();
                    }
                    catch
                    {
                        stack.Push(stemp);
                        continue;
                    }
                    if (strtemp == " ")//表示第一次添加
                    {
                        stack.Push(stemp);
                    }
                    else//比较数据等级大小
                    {
                        if (getIntFromList(stemp) == 0)//判断当前符号是否为右边的括号
                        {
                            try
                            {
                                while ((strtemp = stack.Pop()) != "(")
                                {
                                    Ts.Add(strtemp);
                                }
                                continue;
                            }
                            catch { continue; }

                        }
                        //如果当前符号不是右边括号
                        //前面的是否大于当前的,
                        while (isLowser(strtemp, stemp) && strtemp != "(")
                        {
                            strtemp = stack.Pop();
                            Ts.Add(strtemp);
                            try
                            {
                                strtemp = stack.Peek();
                            }
                            catch
                            {
                                break;
                            }

                        }
                        stack.Push(stemp);
                    }

                }
            }
            string ss = "dd";
            try
            {

                while (ss != " ")
                {
                    ss = stack.Pop();
                    Ts.Add(ss);
                }
            }
            catch
            {
                ss = " ";
            }
            return Ts;
        }
        /// <summary>
        /// 判断栈中的数据级别是否大于于将要加入栈中的符号
        /// </summary>
        /// <param name="Previous">前一个符号</param>
        /// <param name="next">后一个符号</param>
        /// <returns>大于为真,否则为假</returns>
        private static bool isLowser(string Previous, string next)
        {
            if (getIntFromList(Previous) > getIntFromList(next))
            {
                return true;
            }
            return false;
        }
//得到符号的等级
        private static int getIntFromList(string s, int i = 0)
        {

            if (i == mylist.Length)
            {
                return 0;
            } my stmep = mylist[i];
            if (stmep.deouce == s)
            {
                return stmep.i;
            }
            return getIntFromList(s, ++i);
        }
//判断是否是数字
        private static bool isNumber(string c)
        {
            Regex rg = new Regex("\\d");
            return rg.IsMatch(c.ToString());
        }
//分解字符串,得到符号和数字
        private static string ggg(string s)
        {
            int i = 0;
            string temp = "";
            string c1 = s[i].ToString();
            if (s.Length == 1)
            {
                if (!isNumber(c1))
                {
                    return " " + c1;
                }
                else
                    return c1.ToString();
            }
            else
            {
                if (!isNumber(c1))
                {
                    c1 = " " + c1 + " ";
                }

            }
            //相等,就加入集合,并进行下一次查找
            temp += c1;
            return temp + ggg(s.Substring(1));
        }
　　　　//得到最终字符串
        private static string[] getStr(string s)
        {
            List<string> Ts = new List<string>();
            Ts.AddRange(s.Split(' '));
            for (int i = Ts.Count - 1; i > -1; i--)
            {
                if (Ts[i] == "")
                {
                    Ts.RemoveAt(i);
                }
            }
            return Ts.ToArray();
        }
        private static double GetResult(string s, double d1, double d2)
        {
            Icc i = null;
            switch (s)
            {
                case "+": i = new Add(); break;
                case "-": i = new jian(); break;
                case "*": i = new cheng(); break;
                case "/": i = new Chu(); break;
            }
            return i.Count(d1, d2);
        }
        class my
        {
            public int i { get; set; }
            public string deouce { get; set; }
        }
    }
    interface Icc
    {
        double Count(double d1, double d2);
    }
    class Add : Icc
    {
        public double Count(double d1, double d2)
        {
            return d1 + d2;
        }
    }
    class jian : Icc
    {
        public double Count(double d1, double d2)
        {
            return d1 - d2;
        }
    }
    class cheng : Icc
    {
        public double Count(double d1, double d2)
        {
            return d1 * d2;
        }
    }
    class Chu : Icc
    {
        public double Count(double d1, double d2)
        {
            return d1 / d2;
        }
    }