VB.NET,C#字符串计算逻辑meiren777的博客-

我们来看一个计算逻辑:

• (1360 / (480 * 3)) * (30 / 22) + 227 / 480 + 5 * 30

dim out as double=(1360 / (480 * 3)) * (30 / 22) + 227 / 480 + 5 * 30 

这个写起来很简单,运算也能执行
但写成字符串,让代码就无法执行了:

dim outstr as string="(1360 / (480 * 3)) * (30 / 22) + 227 / 480 + 5 * 30" 

有没有办法让这串字符串也能计算出结果呢,例如这样:

dim outstr as string="(1360 / (480 * 3)) * (30 / 22) + 227 / 480 + 5 * 30" dim cal as new CalString dim out as double=cal.Cal_Start(outstr) 

答案是可以的,其计算过程如下:

Imports System.Data Public Class CalString    Dim CF1() As String = {"^", "*", "/", "", "+", "-", "m", "s", "c", "t"}    'sin=s,cos=c,tan=t Public Cal_Log As New List(Of String) Public Class CalDT        Implements IDisposable         Public _DT_THis As New DataTable        Public Sub New()            _DT_THis.Columns.Add("字符")            _DT_THis.Columns.Add("数值", Type.GetType("System.Double"))            _DT_THis.Columns.Add("符号", Type.GetType("System.Boolean")) End Sub Public Function GetMyString() As String Dim MS As String = "" For i As Integer = 0 To _DT_THis.Rows.Count - 1 If _DT_THis.Rows(i)("符号") = True Then                    MS = MS & _DT_THis.Rows(i)("字符") Else                    MS = MS & _DT_THis.Rows(i)("数值") End If Next Return MS        End Function  #Region "IDisposable Support" Private disposedValue As Boolean ' 要检测冗余调用 ' IDisposable Protected Overridable Sub Dispose(disposing As Boolean) If Not disposedValue Then If disposing Then ' TODO: 释放托管状态(托管对象)。 End If If IsNothing(_DT_THis) = False Then                    _DT_THis.Dispose()                    _DT_THis = Nothing End If ' TODO: 释放未托管资源(未托管对象)并在以下内容中替代 Finalize()。 ' TODO: 将大型字段设置为 null。 End If            disposedValue = True End Sub ' TODO: 仅当以上 Dispose(disposing As Boolean)拥有用于释放未托管资源的代码时才替代 Finalize()。 'Protected Overrides Sub Finalize() '    ' 请勿更改此代码。将清理代码放入以上 Dispose(disposing As Boolean)中。 '    Dispose(False) '    MyBase.Finalize() 'End Sub ' Visual Basic 添加此代码以正确实现可释放模式。 Public Sub Dispose() Implements IDisposable.Dispose            ' 请勿更改此代码。将清理代码放入以上 Dispose(disposing As Boolean)中。            Dispose(True) ' TODO: 如果在以上内容中替代了 Finalize()，则取消注释以下行。 ' GC.SuppressFinalize(Me) End Sub #End Region    End Class 'mod转化为m Private Sub CalAllTeshu(_calDT As CalDT)        Cal_TeShu("s", _calDT, "sin")        CreateCalLog("sin", _calDT.GetMyString)        Cal_TeShu("c", _calDT, "cos")        CreateCalLog("cos", _calDT.GetMyString)        Cal_TeShu("t", _calDT, "tan")        CreateCalLog("tan", _calDT.GetMyString) End Sub Private Function ReplaceTeShu(_S As String) Dim TS As String = _S        TS = TS.Replace("sin", "s")        TS = TS.Replace("cos", "c")        TS = TS.Replace("tan", "t") Return TS    End Function Public Function Cal_teshuall(ByVal Nowc As String, s1 As Double) As Double Select Case Nowc            Case "s" Return Math.Sin(s1) Case "c" Return Math.Cos(s1) Case "t" Return Math.Tan(s1) Case Else Throw New Exception("出现无法识别的运算符:" & Nowc) End Select End Function Private Function ModToM(ByVal _S As String) As String Dim TS As String = _S        TS = TS.Replace("mode", "m")        TS = TS.Replace("mod", "m") Return TS    End Function Public Function IsHave符号(ByVal _S As String, _CalDT As CalDT) As Boolean Dim dt_this = _CalDT._DT_THis        For i As Integer = dt_this.Rows.Count - 1 To 0 Step -1 If dt_this.Rows(i)("符号") = True Then If dt_this.Rows(i)("字符") = _S Then Return True End If End If Next Return False End Function Public Sub Cal_TeShu(Nowc As String, _CalDT As CalDT, NowName As String) Dim dt_this = _CalDT._DT_THis        Try Do While IsHave符号(Nowc, _CalDT) = True For i As Integer = 0 To dt_this.Rows.Count - 1 If dt_this.Rows(i)("符号") = True Then If dt_this.Rows(i)("字符") = Nowc Then Dim c1 As Double = dt_this.Rows(i + 1)("数值") Dim GCV As Double = Cal_teshuall(Nowc, c1)                            dt_this.Rows(i + 1)("数值") = GCV                            dt_this.Rows.RemoveAt(i) Exit For End If End If Next Loop Catch ex As Exception            Throw New Exception(NowName & "附近有错误发生,详细错误如下：" & vbCrLf & ex.Message) End Try End Sub Public Sub Cal_Value(NowC As String, _CalDT As CalDT) Dim dt_this = _CalDT._DT_THis        Try Do While IsHave符号(NowC, _CalDT) = True For i As Integer = 0 To dt_this.Rows.Count - 1 If dt_this.Rows(i)("符号") = True Then If dt_this.Rows(i)("字符") = NowC Then Dim c1 As Double = dt_this.Rows(i - 1)("数值") Dim c2 As Double = dt_this.Rows(i + 1)("数值") Dim GCV As Double = Cal_all(NowC, c1, c2)                            dt_this.Rows(i - 1)("数值") = GCV                            dt_this.Rows.RemoveAt(i + 1)                            dt_this.Rows.RemoveAt(i) Exit For End If End If Next Loop Catch ex As Exception            Throw New Exception(NowC & "附近有错误发生,详细错误如下：" & vbCrLf & ex.Message) End Try End Sub Public Sub Cal_Value_Together(NowC1 As String, Nowc2 As String, _CalDT As CalDT) Dim dt_this = _CalDT._DT_THis        Try Do While (IsHave符号(NowC1, _CalDT) = True Or IsHave符号(Nowc2, _CalDT)) For i As Integer = 0 To dt_this.Rows.Count - 1 If dt_this.Rows(i)("符号") = True Then If dt_this.Rows(i)("字符") = NowC1 Then Dim c1 As Double = dt_this.Rows(i - 1)("数值") Dim c2 As Double = dt_this.Rows(i + 1)("数值") Dim GCV As Double = Cal_all(NowC1, c1, c2)                            dt_this.Rows(i - 1)("数值") = GCV                            dt_this.Rows.RemoveAt(i + 1)                            dt_this.Rows.RemoveAt(i) Exit For End If If dt_this.Rows(i)("字符") = Nowc2 Then Dim c1 As Double = dt_this.Rows(i - 1)("数值") Dim c2 As Double = dt_this.Rows(i + 1)("数值") Dim GCV As Double = Cal_all(Nowc2, c1, c2)                            dt_this.Rows(i - 1)("数值") = GCV                            dt_this.Rows.RemoveAt(i + 1)                            dt_this.Rows.RemoveAt(i) Exit For End If End If Next Loop Catch ex As Exception            Throw New Exception(NowC1 & Nowc2 & "附近有错误发生,详细错误如下：" & vbCrLf & ex.Message) End Try End Sub Public Function Cal_Start(SText As String) As Double Dim RD As Double = 0 Try            Cal_Log.Clear() Dim _s As String = SText.Replace(" ", "").ToLower  '去掉所有空格，小写化            _s = ModToM(_s) 'mod转换为m '括号转换            _s = _s.Replace("（", "(")            _s = _s.Replace("）", "(")            _s = ReplaceTeShu(_s)            RD = Cal_Del括号(_s)            CreateCalLog("结果", RD, True) Return RD        Catch ex As Exception            CreateCalLog("结果", "错误：" & ex.Message, True) Return RD        Finally End Try End Function Public Function Cal_Del括号(_S As String) As Double Dim I_Start As Integer = 0 Dim I_end As Integer = 0 Dim GetS As String = "" For i As Integer = 0 To _S.Length - 1 If _S(i) = "(" Then I_Start = i + 1 If _S(i) = ")" Then I_end = i + 1 If I_Start <> 0 And I_end > I_Start Then Exit For Next        CreateCalLog("括号运算", _S) If I_Start = 0 And I_Start = 0 Then Return Cal_四则运算(_S) End If If I_end - I_Start > 1 Then Dim S1 As String = Mid(_S, 1, I_Start - 1) Dim SC As String = Cal_四则运算(Mid(_S, I_Start + 1, I_end - I_Start - 1)) Dim S2 As String = Mid(_S, I_end + 1)            _S = S1 & SC & S2            Dim In1 As Integer = InStr(_S, "(") Dim In2 As Integer = InStr(_S, ")") If In1 > 0 And In2 > 0 Then Return Cal_Del括号(_S) ElseIf In1 = 0 And In2 = 0 Then Return Cal_四则运算(_S) Else Throw New Exception("括号附近出现错误！") End If Else Throw New Exception("括号附近出现错误！") End If Throw New Exception("判断括号出现异常，请联程序开发员处理！") End Function Private Function Cal_四则运算(S1_S As String) As Double Dim S1_C As New CalDT        Dim I_Start As Integer = 1 If S1_S.Length = 1 Then Return Val(S1_S) For i As Integer = 0 To S1_S.Length - 1 Dim NowS1S As String = S1_S(i) Dim NowS1S_Next As String = "" Dim NowS1S_Per As String = "" If i <> 0 Then                NowS1S_Per = S1_S(i - 1) End If If S1_S.Length - 1 <> i Then                NowS1S_Next = S1_S(i + 1) End If If NowS1S_Next = "" Then Dim NewC = S1_C._DT_THis.NewRow                NewC("字符") = Mid(S1_S, I_Start)                NewC("符号") = False                ChangeStrTOValue(NewC)                S1_C._DT_THis.Rows.Add(NewC) Else If CheckCF1(NowS1S_Per, NowS1S, NowS1S_Next) = True Then If NowS1S_Per <> "" Then If Is符号(NowS1S_Per) = False Then Dim NewC = S1_C._DT_THis.NewRow                            NewC("字符") = Mid(S1_S, I_Start, i - I_Start + 1)                            NewC("符号") = False                            ChangeStrTOValue(NewC)                            S1_C._DT_THis.Rows.Add(NewC) End If End If Dim NewC1 = S1_C._DT_THis.NewRow                    NewC1("字符") = NowS1S                    NewC1("符号") = True                    S1_C._DT_THis.Rows.Add(NewC1)                    I_Start = i + 2 End If End If Next        CreateCalLog("分支运行", S1_C.GetMyString)        CalAllTeshu(S1_C)        Cal_Value("^", S1_C)        CreateCalLog("^", S1_C.GetMyString)        Cal_Value_Together("*", "/", S1_C)        CreateCalLog("*,/", S1_C.GetMyString)        Cal_Value("", S1_C)        CreateCalLog("", S1_C.GetMyString)        Cal_Value("m", S1_C)        CreateCalLog("Mod", S1_C.GetMyString)        Cal_Value_Together("+", "-", S1_C)        CreateCalLog("+,-", S1_C.GetMyString) Return Val(S1_C.GetMyString) End Function Public Function Cal_all(ByVal Nowc As String, s1 As Double, s2 As Double) As Double Select Case Nowc            Case "^" Return s1 ^ s2            Case "*" Return s1 * s2            Case "/" If s2 = 0 Then Throw New Exception("除数不能为0！") End If Return s1 / s2            Case ""                If s2 = 0 Then Throw New Exception("除数不能为0！") End If Return s1  s2            Case "m" If s2 = 0 Then Throw New Exception("除数不能为0！") End If Return s1 Mod s2            Case "+" Return s1 + s2            Case "-" Return s1 - s2            Case Else Throw New Exception("找不到符号'" & Nowc & "'") End Select End Function Private Sub ChangeStrTOValue(ByRef _ES As DataRow) Try If _ES("符号") = False Then Dim I_E As Integer = InStr(_ES("字符"), "e") Dim i_加 As Integer = InStr(_ES("字符"), "+") Dim i1 As Integer = 0 Dim i2 As Integer = 0 If I_E > i_加 Then                    i2 = I_E                    If i_加 <> 0 Then                        i1 = i_加                    Else                        i1 = I_E                    End If Else                    i2 = i_加                    If i_加 <> 0 Then                        i1 = I_E                    Else                        i1 = i_加                    End If End If If i1 > 0 And i2 > 0 Then                    _ES("数值") = Val(Mid(_ES("字符"), 1, i1)) * 10 ^ Val(Mid(_ES("字符"), i2 + 1)) Else                    _ES("数值") = Val(_ES("字符")) End If End If Catch ex As Exception            Throw New Exception("e附近有错误发生!") End Try End Sub Private Function CheckCF1(ByVal _S_per As String, ByVal _S As String, ByVal _S_Next As String) As Boolean If _S = "+" And _S_Next = "e" Then Return False If _S = "e" And _S_Next = "+" Then Return False If _S = "+" And _S_per = "e" Then Return False If _S = "e" And _S_per = "+" Then Return False If (_S_per = "" Or _S_per = "e") And _S = "-" Then Return False If Is符号(_S_per) = True Then If _S = "-" Then Return False End If 'If Is符号(_S) = True Then '    Throw New Exception(_S_per & _S & "附近发生错误!") 'End If End If For i As Integer = 0 To CF1.Length - 1 If CF1(i) = _S Then Return True Next Return False End Function Private Function Is符号(ByVal _S) As Boolean For i As Integer = 0 To CF1.Length - 1 If CF1(i) = _S Then Return True Next Return False End Function Dim LastValString As String = "" Private Sub CreateCalLog(ByVal SS_Per As String, ByVal SS_Value As String, Optional MustAdd As Boolean = False) If LastValString <> SS_Value Or MustAdd = True Then Dim s1 As String = "计算元素(" & SS_Per & "):"            Cal_Log.Add(s1 & SS_Value)            LastValString = SS_Value        End If End Sub End Class