栈实现字符串表达式计算

类别:.NET开发 点击:0 评论:0 推荐:

最近频繁解决计算方面的问题,其中就有实现字符串表达式计算返回结果值需求,通过使用栈实现,需要定义运算符号优先级,其它就不细说,代码如下:

csStack.cs:

using System;

namespace PYHB
{
 /// <summary>
 /// 栈堆设定。

 /// 日期:2005-05-17
 /// </summary>
 public class clsStack
 {
  private long Top;    //栈最大序号
  private int MaxSize; // MaxSize 栈的容量
  private string[] Element;
  public clsStack()
  {
   //
   // TODO: 在此处添加构造函数逻辑
   //
   Top=-1;
  }
  /// <summary>
  /// 设定栈大最大容量
  /// </summary>
  /// <param name="Size"></param>
  public void Initialize(int Size)
  {
   MaxSize=Size;
   Element=new string[Size];
  }
  /// <summary>
  /// 入栈
  /// </summary>
  /// <param name="strItem"></param>
  public void Push(string strItem)
  {
   if(!IsFull())
   {
    Top=Top+1;
    Element[Top] = strItem;
   }
   
  }
  /// <summary>
  /// 出栈
  /// </summary>
  /// <returns></returns>
  public string Pop()
  {
   string strRtn=" ";
   if(!IsEmptly())
   {
    strRtn = Element[Top];
    Top=Top-1;
   }
   return strRtn;
  }
  public string  GetTop()
  {
   string strRtn=" ";
   if(!IsEmptly())
   {
    strRtn = Element[Top];
   }
   return strRtn;
  }
  public bool IsFull()
  {
   bool IsFull=Top==(MaxSize-1)?true:false;
   return IsFull;
  }
  public void MakeEmptly()
  {
   Top = -1;
  }
  public bool IsEmptly()
  {
   bool IsEmptly=Top==-1?true:false;
   return IsEmptly;
  }

 }
}

calculate.cs

using System;
using System.Text;
using System.Windows.Forms;

namespace PYHB
{
 /// <summary>
 /// 字符串表达式计算实现,返回计算结果字符数组
 
 /// 日期:2005-05-17
 /// </summary>
 public class Calculate
 {
  private clsStack S=new clsStack();
  public Calculate()
  {
   //
   // TODO: 在此处添加构造函数逻辑
   //
  }
  
  
  /// <summary>
  /// 根据数字表达式字符串数组,返回计算结果字符数组
  /// </summary>
  /// <param name="strSoure">strSour 中缀表达式字符串,头部没有“#”,尾部需要加上“#”</param>
  /// <returns>计算结果</returns>
  public string[] Run(string[] strSoure)
  {
   if(strSoure==null)
   {
    return null;
   }
   string[] dRtn=new string[strSoure.Length];
   for(int k=0;k<strSoure.Length;k++)
   {
    string[] ATemp;
    string strRPN;
    strRPN=GetRPN(strSoure[k]);
    try
    {
     ATemp=strRPN.Trim().Split(' ');
     for(int i=0;i<ATemp.Length;i++)
     {
      if(sysFun.IsNumber(ATemp[i]))
       S.Push(ATemp[i]);
      else
       DoOperate(ATemp[i]);
     }
   
     dRtn[k]=S.Pop();
    }
    catch{}
   }
   return dRtn;
  }
  /// <summary>
  ///  Run 返回后缀表达式
  ///  strSour 中缀表达式字符串,头部没有“#”,尾部需要加上“#”
  ///  String  后缀表达式字符串,头尾都没有“#”

  /// </summary>
  /// <param name="strSource"></param>
  /// <returns></returns>
  private string GetRPN(string strSource)
  {
   string[] ATemp;
   string strRPN="",Y;
   ATemp=strSource.Trim().Split(' ');
   S.Initialize(ATemp.Length);
   S.MakeEmptly();
   S.Push("#");
   try
   {
    for(int k=0;k<ATemp.Length;k++)
    {
     //数字
     if(sysFun.IsNumber(ATemp[k]))
     {
      strRPN += " "+ATemp[k];
     }
      //字符
     else
     {
      if(ATemp[k]==")")
      {
       do
       {
        Y=S.Pop();
        if(Y!="(")
         strRPN += " "+Y;
       }
       while(Y.Trim()!="(");
      }
      else
      {
       do
       {
        Y = S.Pop();
        if (GetISP(Y) > GetICP(ATemp[k]))
         strRPN += " "+Y;
       }
       while(GetISP(Y) > GetICP(ATemp[k]));
       S.Push(Y);
       S.Push(ATemp[k]);
      }
     }
    }
    do
    {
     Y=S.Pop();
     if(Y!="#")
      strRPN+=" "+Y;
    }
    while(Y!="#");
   }
   catch{}
   return strRPN;
  }

  #region 运算符优先级定义
  private enum isp
  {
   s35 = 0,
   s40 = 1,
   s94 = 7,
   s42 = 5,
   s47 = 5,
   s37 = 5,
   s43 = 3,
   s45 = 3,
   s41 = 8
  }
  private enum icp
  {
   s35 = 0,
   s40 = 8,
   s94 = 6,
   s42 = 4,
   s47 = 4,
   s37 = 4,
   s43 = 2,
   s45 = 2,
   s41 = 1
  }
  private int GetISP(string a1)
  {
   Encoding ascii =Encoding.ASCII;
   byte[] a=ascii.GetBytes(a1);
   switch(Convert.ToInt32(a[0]))
   {
    case 35:
     return (int)isp.s35;

    case 40:
     return (int)isp.s40;
     
    case 94:
     return (int)isp.s94;
     
    case 42:
     return (int)isp.s42;
     
    case 47:
     return (int)isp.s47;
     
    case 37:
     return (int)isp.s37;
     
    case 43:
     return (int)isp.s43;
     
    case 45:
     return (int)isp.s45;
     
    case 41:
     return (int)isp.s41;
    default:
     return (int)isp.s35;
   }
   
  }
  private int GetICP(string a1)
  {
   Encoding ascii =Encoding.ASCII;
   byte[] a=ascii.GetBytes(a1);
   switch(Convert.ToInt32(a[0]))
   {
    case 35:
     return (int)icp.s35;
     
    case 40:
     return (int)icp.s40;
     
    case 94:
     return (int)isp.s94;
     
    case 42:
     return (int)icp.s42;
     
    case 47:
     return (int)icp.s47;
     
    case 37:
     return (int)icp.s37;
     
    case 43:
     return (int)icp.s43;
     
    case 45:
     return (int)icp.s45;
     
    case 41:
     return (int)icp.s41;
    default:
     return (int)icp.s35;
    
   }
   
  }
  #endregion

  /// <summary>
  /// 判断是否存在左右数字,并且复制
  /// </summary>
  /// <param name="dLeft">左数值</param>
  /// <param name="dRight">右的数值</param>
  /// <returns>是否成功</returns>
  private bool GetTwoItem(ref decimal dLeft,ref decimal dRight)
  {
   bool bRtn=true;
   try
   {
    if(S.IsEmptly())
     return false;
    else
     dRight = Convert.ToDecimal(S.Pop());
    if(S.IsEmptly())
     return false;
    else
     dLeft = Convert.ToDecimal(S.Pop());
   }
   catch
   {
   }
   return bRtn;
  }
  /// <summary>
  /// 根据运算符号计算,并且把计算结果以字符形式填充入栈
  /// </summary>
  /// <param name="op"></param>
  private void DoOperate(string op)
  {
   decimal NumLeft=0,NumRight=0;
   bool r;
   r=GetTwoItem(ref NumLeft,ref NumRight);
   if(r)
   {
    switch(op.Trim())
    {
     case "+":
      S.Push((NumLeft+NumRight).ToString());
      break;
     case "-":
      S.Push((NumLeft-NumRight).ToString());
      break;
     case "*":
      S.Push((NumLeft*NumRight).ToString());
      break;
     case "/":
      if(NumRight==0)
       S.Push("0");
      else
       S.Push((NumLeft/NumRight).ToString());
      break;

    }
   }
  }

}

}

本文地址:http://com.8s8s.com/it/it40958.htm