1 /******************************************************************  2  * 创 建 人：  SamWang  3  * 创建时间：  2011-11-29  4  * 描    述：  5  *             计算器类：能直接对表达式进行计算，支持变量  6  * 原    理：  将表达式按字符压入堆栈中，然后按照各操作符的级别进行处理  7  * 版    本：  V1.0        8  * 环    境：  VS2005  9 ******************************************************************/ 10 using System; 11 using System.Collections.Generic; 12 using System.Text; 13 using System.Windows.Forms; 14 using System.Collections; 15  16 namespace LingDang.CRM.UI.Client 17 { 18     public class Calculator 19     { 20         private string _expression; 21         private Stack s; 22         private string[] values; 23  24         /// 
 25         /// 构造函数 26         /// 
 27         /// 表达式 28         /// 变量值数组 29         public Calculator(string expression, string[] varValues) 30         { 31             this._expression = expression.ToLower(); 32             s = new Stack(); 33             values = varValues; 34         } 35  36         /// 
 37         /// 构造函数 38         /// 
 39         /// 表达式 40         public Calculator(string expression) 41         { 42             this._expression = expression; 43             s = new Stack(); 44         } 45  46         /// 
 47         /// 总运行 48         /// 
 49         /// 
      50         public double Run() 51         { 52             string expression = PostFix(); 53             string[] aryString = expression.Split('|'); 54  55             foreach (string str in aryString) 56             { 57                 if (IsNumber(str) || IsVarible(str[0])) 58                 { 59                     double d; 60                     if (IsVarible(str[0])) 61                     { 62                         d = Convert.ToDouble(GetValue(str[0])); 63                     } 64                     else 65                     { 66                         d = Convert.ToDouble(str.ToString()); 67                     } 68                     AddOperands(d); 69                 } 70                 else 71                 { 72                     DoOperator(str); 73                 } 74  75             } 76             return (double)s.Pop(); 77         } 78  79  80         private bool IsNumber(string str) 81         { 82             if (str.Length > 1) 83             { 84                 return true; 85             } 86             else 87             { 88                 return Char.IsDigit(str[0]); 89             } 90         } 91  92         /// 
 93         /// 判断是否为变量，变量范围为a-z 94         /// 
 95         ///  96         /// 
      97         private bool IsVarible(char c) 98         { 99             if (c >= 'a' && c <= 'z')100             {101                 return true;102             }103             else104             {105                 return false;106             }107         }108 109 110         private void AddOperands(double val)111         {112             s.Push(val);113         }114 115         /// 
116         /// 得到公式左右运算数117         /// 
118         /// 119         /// 120         /// 
     121         private bool GetTwoOperands(out double left, out double right)122         {123             try124             {125                 right = (double)s.Pop();126                 left = (double)s.Pop();127             }128             catch (InvalidOperationException)129             {130                 right = 0;131                 left = 0;132                 return false;133             }134             return true;135         }136 137         /// 
138         /// 计算操作139         /// 
140         /// 运算符141         private void DoOperator(string op)142         {143             double left, right;144             bool result = GetTwoOperands(out left, out right);145             if (result)146             {147                 switch (op)148                 {149                     case "+": s.Push(left + right); break;150                     case "-": s.Push(left - right); break;151                     case "*": s.Push(left * right); break;152                     case "/":153                         if (right == 0.0)154                         {155                             s.Clear();156                             //Divide by 0!157                             throw new Exception("除数不能为零");158                         }159                         else160                             s.Push(left / right);161                         break;162                     case "^":163                         s.Push(Math.Pow(left, right));164                         break;165                 }166             }167             else168             {169                 s.Clear();170             }171         }172 173         /// 
174         /// 解析为后缀表达式175         /// 
176         /// 
     177         public string PostFix()178         {179             string str = this._expression + "#";180             char tempc;181             char[] chars = str.ToCharArray();182             Stack ts = new Stack();183             ts.Push('#');184             string str1 = "";185             string tmpStr = "";186             bool isNum = false;187             foreach (char c in chars)188             {189                 if (Char.IsDigit(c) || IsVarible(c) || c == '.')190                 {191                     tmpStr += c.ToString();192                     isNum = true;193                 }194                 else195                 {196                     if (isNum)197                     {198                         str1 += tmpStr + "|";199                         tmpStr = "";200                     }201                     isNum = false;202                     if (c == ')')203                     {204                         for (tempc = Convert.ToChar(ts.Pop()); tempc != '('; tempc = Convert.ToChar(ts.Pop()))205                             str1 += tempc.ToString() + "|";206                     }207                     else208                     {209                         for (tempc = Convert.ToChar(ts.Pop()); Isp(tempc) > Icp(c); tempc = Convert.ToChar(ts.Pop()))210                             str1 += tempc.ToString() + "|";211                         ts.Push(tempc);212                         ts.Push(c);213                     }214                 }215             }216             return str1.Substring(0, str1.Length - 1);217         }218 219         /// 
220         /// 根据变量名得到对应的值221         /// 
222         /// 变量名：A-Z223         /// 
     224         private string GetValue(char c)225         {226             string result = "0";227             //变量对应的数组位置228             int index = Convert.ToInt32(c) - Convert.ToInt32('a');229             if (index < values.Length)230             {231                 result = values[index].ToString();232             }233             return result;234         }235 236         private int Isp(char c)237         {238             int k;239             switch (c)240             {241                 case '#': k = 0; break;242                 case '(': k = 1; break;243                 case '^': k = 7; break;244                 case '*':245                 case '/':246                 case '%': k = 5; break;247                 case '+':248                 case '-': k = 3; break;249                 case ')': k = 8; break;250                 default:251                     //Unknown operator!252                     throw new Exception("无效操作符："+c.ToString());253             }254             return k;255         }256 257         private int Icp(char c)258         {259             int k;260             switch (c)261             {262                 case '#': k = 0; break;263                 case '(': k = 8; break;264                 case '^': k = 6; break;265                 case '*':266                 case '/':267                 case '%': k = 4; break;268                 case '+':269                 case '-': k = 2; break;270                 case ')': k = 1; break;271                 default:272                     //Unknown operator!273                     throw new Exception("无效操作符：" + c.ToString());274             }275             return k;276         }277     }278 }

 

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