VB怎么输入表达式计算得到结果?

发布网友发布时间：2023-11-04 02:26

共2个回答

热心网友时间：2024-12-13 17:48

  Function EvaluateB(ByRef Bdsz As String) As Double
        '思路：先计算括号内，再依次计算括号外。大多用拼音第一字母命名
        Dim LenBdsz As Integer   '计算表达式长度
        Dim LskhStr(3) As String      '临时括号值，即括号将原表达式分隔成三段 LskhStr（0）为总计算值
        Dim i, j As Integer
        On Error GoTo err1
        LskhStr(0) = StrConv(Trim(Bdsz), vbNarrow) '更换全角括号为半角
Xh:     '循环去括号
        LenBdsz = Len(LskhStr(0))
        i = InStr(LskhStr(0), ")")
        If i > 0 Then
            j = InStrRev(Mid(LskhStr(0), 1, i), "(")
            If j > 0 Then
                LskhStr(1) = Mid(LskhStr(0), 1, j - 1)
                LskhStr(2) = Mid(LskhStr(0), j + 1, i - j - 1)
                LskhStr(3) = Mid(LskhStr(0), i + 1, LenBdsz - i)
                LskhStr(2) = CalcB(Trim(LskhStr(2)))     '最内括号计算
                LskhStr(0) = LskhStr(1) & LskhStr(2) & LskhStr(3)
                GoTo Xh
            Else
                GoTo err1
            End If
        End If
        LskhStr(0) = CalcB(LskhStr(0))      'calc.Eval(LskhStr(0)).ToString
        Return LskhStr(0)
        Exit Function
err1:
        Return 0
    End Function


    Function CalcB(ByRef str1 As String) As String     '仅四则运算，+-*/无括号

        Dim Cn2 As String, Str2(4) As String
        Dim LenStr As Integer, i As Integer, j As Integer
        '''''''''''''''''''''''''''''''''''
Xh2:       '先计算"/"    此前可增加开方,乘方等优先计算符的计算
        LenStr = Len(str1)
        i = InStr(str1, "/")
        If i > 0 Then
            If i = 1 Or i = LenStr Then
                Return "表达式错误"
                Exit Function
            End If
            For j = i - 1 To 1 Step -1
                Cn2 = Mid(str1, j, 1)
                If Cn2 = "+" Or Cn2 = "-" Or Cn2 = "/" Or Cn2 = "*" Then
                    Str2(1) = Mid(str1, 1, j)
                    Str2(2) = Mid(str1, j + 1, i - j - 1)
                    Exit For
                End If
                If j = 1 Then
                    Str2(1) = ""
                    Str2(2) = Mid(str1, 1, i - 1)
                End If
            Next
            For j = i + 1 To LenStr
                Cn2 = Mid(str1, j, 1)
                If Cn2 = "+" Or Cn2 = "-" Or Cn2 = "/" Or Cn2 = "*" Then
                    Str2(3) = Mid(str1, i + 1, j - i - 1)
                    Str2(4) = Mid(str1, j， LenStr - j + 1)
                    Exit For
                End If
                If j = LenStr Then
                    Str2(3) = Mid(str1, i + 1, LenStr - i)
                    Str2(4) = ""
                End If
            Next
            str1 = Trim(Str2(1) & Trim(Str(Val(Trim(Str2(2))) / Val(Trim(Str2(3))))) & Trim(Str2(4)))
            GoTo Xh2
        End If

Xh1:
        LenStr = Len(str1)
        i = InStr(str1, "*")
        If i > 0 Then
            If i = 1 Or i = LenStr Then
                Return "表达式错误"
                Exit Function
            End If
            For j = i - 1 To 1 Step -1
                Cn2 = Mid(str1, j, 1)
                If Cn2 = "+" Or Cn2 = "-" Or Cn2 = "/" Or Cn2 = "*" Then
                    Str2(1) = Mid(str1, 1, j)
                    Str2(2) = Mid(str1, j + 1, i - j - 1)
                    Exit For
                End If
                If j = 1 Then
                    Str2(1) = ""
                    Str2(2) = Mid(str1, 1, i - 1)
                End If
            Next
            For j = i + 1 To LenStr
                Cn2 = Mid(str1, j, 1)
                If Cn2 = "+" Or Cn2 = "-" Or Cn2 = "/" Or Cn2 = "*" Then
                    Str2(3) = Mid(str1, i + 1, j - i - 1)
                    Str2(4) = Mid(str1, j， LenStr - j + 1)
                    Exit For
                End If
                If j = LenStr Then
                    Str2(3) = Mid(str1, i + 1, LenStr - i)
                    Str2(4) = ""
                End If
            Next
            str1 = Trim(Str2(1) & Trim(Str(Val(Trim(Str2(2))) * Val(Trim(Str2(3))))) & Trim(Str2(4)))
            GoTo Xh1
        End If

Xh4:
        LenStr = Len(str1)
        i = InStr(2, str1, "-")
        If i > 0 Then
            If i = LenStr Then
                Return "表达式错误"
                Exit Function
            End If
            For j = i - 1 To 1 Step -1
                Cn2 = Mid(str1, j, 1)
                If (Cn2 = "+" Or Cn2 = "-" Or Cn2 = "/" Or Cn2 = "*") And j > 1 Then
                    Str2(1) = Mid(str1, 1, j)
                    Str2(2) = Mid(str1, j + 1, i - j - 1)
                    Exit For
                Else
                    If j = 1 Then
                        Str2(1) = ""
                        Str2(2) = Mid(str1, 1, i - 1)
                    End If
                End If
            Next
            For j = i + 1 To LenStr
                Cn2 = Mid(str1, j, 1)
                If Cn2 = "+" Or Cn2 = "-" Or Cn2 = "/" Or Cn2 = "*" Then
                    Str2(3) = Mid(str1, i, j - i)
                    Str2(4) = Mid(str1, j， LenStr - j + 1)
                    Exit For
                End If
                If j = LenStr Then
                    Str2(3) = Mid(str1, i, LenStr - i + 1)
                    Str2(4) = ""
                End If
            Next
            If Mid(Str(Val(Str2(2)) + Val(Str2(3))), 1, 1) = "-" Then
                If Str2(1) <> "" Then
                    If Mid(Str2(1), Len(Str2(1)), 1) = "+" Then
                        Str2(1) = Mid(Str2(1), 1, Len(Str2(1)) - 1)
                    End If
                End If
            End If
            str1 = Trim(Str2(1) & Trim(Str(Val(Trim(Str2(2))) + Val(Trim(Str2(3))))) & Str2(4))
            GoTo Xh4
        End If
Xh3:
        LenStr = Len(str1)
        i = InStr(str1, "+")
        If i > 0 Then
            If i = 1 Or i = LenStr Then
                Return "表达式错误"
                Exit Function
            End If
            For j = i - 1 To 1 Step -1
                Cn2 = Mid(str1, j, 1)
                If Cn2 = "+" Or Cn2 = "-" Or Cn2 = "/" Or Cn2 = "*" Then
                    If Mid(str1, 1, 1) = "-" Then
                        Str2(1) = ""
                        Str2(2) = Mid(str1, 1, i - j)
                    Else
                        Str2(1) = Mid(str1, 1, j)
                        Str2(2) = Mid(str1, j + 1, i - j - 1)
                    End If
                    Exit For
                End If
                If j = 1 Then
                    Str2(1) = ""
                    Str2(2) = Mid(str1, 1, i - 1)
                End If
            Next
            For j = i + 1 To LenStr
                Cn2 = Mid(str1, j, 1)
                If Cn2 = "+" Or Cn2 = "-" Or Cn2 = "/" Or Cn2 = "*" Then
                    Str2(3) = Mid(str1, i + 1, j - i - 1)
                    Str2(4) = Mid(str1, j， LenStr - j + 1)
                    Exit For
                End If
                If j = LenStr Then
                    Str2(3) = Mid(str1, i + 1, LenStr - i)
                    Str2(4) = ""
                End If
            Next
            str1 = Trim(Str2(1) & Trim(Str(Val(Trim(Str2(2))) + Val(Trim(Str2(3))))) & Str2(4))
            GoTo Xh3
        End If
        Return str1
    End Function

热心网友时间：2024-12-13 17:49

Private Sub Command1_Click()
Dim ex As String, res As String, calc As Object
Set calc = CreateObject("MSScriptControl.ScriptControl")
calc.Language = "vbscript"
ex = Text1.Text
rs = calc.Eval(ex)
Text2.Text = rs
End Sub