c#实现科学计算器 实现篇之常数表实现

常数表是用来在计算器中提供常数数据用的，为了使提供常数更加方便，所以设计常数表类。大家一定会发现，在这张表中除了常数外，还有许多变量，这里之所以叫常数表，是因为这些变量的值其实是用来替换表达式中的相应字符串的。

    /**//// 

    /// 常数及变量表
    /// 
    public class ConstantTable
    {
        public static double AX=0.0;    //数存储变量A
        public static double BX=0.0;    //数存储变量B
        public static double CX=0.0;    //数存储变量C
        public static double DX=0.0;    //数存储变量D
        public static double EX=0.0;    //数存储变量E
        public static double FX=0.0;    //数存储变量F
        public static double ANS=0.0;    //最终结果存储变量

        public const double PI=Math.PI;    //常数PI
        public readonly static double EXP=Math.Exp(1);    //常数e
        /**//// 

        /// 保存浮点数到一个变量
        /// 
        /// 变量名
        /// 值
        public static void SaveTo(string x,double Value)
        {
            switch(x.ToUpper())
            {
                case "A":
                    ConstantTable.AX=Value;
                    break;
                case "B":
                    ConstantTable.BX=Value;
                    break;
                case "C":
                    ConstantTable.CX=Value;
                    break;
                case "D":
                    ConstantTable.DX=Value;
                    break;
                case "E":
                    ConstantTable.EX=Value;
                    break;
                case "F":
                    ConstantTable.FX=Value;
                    break;
                default:
                    ConstantTable.ANS=Value;
                    break;
            }
        }
        /**//// 

        /// 从一个变量读取一个浮点值
        /// 
        /// 变量名
        /// 
        public static double GetFrom(string x)
        {
            switch(x.ToUpper())
            {
                case "A":
                    return ConstantTable.AX;
                case "B":
                    return ConstantTable.BX;
                case "C":
                    return ConstantTable.CX;
                case "D":
                    return ConstantTable.DX;
                case "E":
                    return ConstantTable.EX;
                case "F":
                    return ConstantTable.FX;
                default:
                    return ConstantTable.ANS;
            }        
        }