从网上下的一个用正则表达是做的表达式计算器，它的加减法有问题，哪一位高手能够帮助修改正确，谢谢！！！
从网上下的一个用正则表达是做的表达式计算器，它的加减法有问题，哪一位高手能够帮助修改正确，谢谢！！！
如4-2*(1+1)=4、4+2*(1+1)=12
4+2*(2+3)计算不正确 2*(2+3)+4 就能计算正确
Imports System.Text.RegularExpressionsPublic Class Form2 Public Primitives As New Hashtable Function Evaluate(ByVal expr As String) As Double Const Num As String = "(\-?\d+\.?\d*)" Const Func1 As String = "(exp|log|log10|abs|sqr|sqrt|sin|cos|tan|asin|acos|atan)" Const Func2 As String = "(atan2)" Const FuncN As String = "(min|max)" Const Constants As String = "(e|pi)" Dim rePower As New Regex(Num & "\s*(\^)s*" & Num) Dim reAddSub As New Regex(Num & "\s*([-+])s*" & Num) Dim reMulDiv As New Regex(Num & "\s*([*/])s*" & Num) Dim reFunc1 As New Regex(Func1 & "\(\s*((\((?<o>\()|(?<-o>\))|[^()]+(?(o)(?!)))+)\s*\)", RegexOptions.IgnoreCase) Dim reFunc2 As New Regex(Func2 & "\(\s*" & Num & "\s*,\s*" & Num & "\s*\)", RegexOptions.IgnoreCase) Dim reFuncN As New Regex(FuncN & "\((\s*" & Num & "\s*,)+\s*" & Num & "\s*\)", RegexOptions.IgnoreCase) Dim reSign1 As New Regex("([-+/*^])\s*\+") Dim reSign2 As New Regex("\-\s*\-") Dim rePar As New Regex("(?<![A-Za-z0-9])\(\s*([-+]?\d+.?\d*)\s*\)") Dim reNum As New Regex("^\s*[-+]?\d+\.?\d*\s*$") Dim reConst As New Regex("\s*" & Constants & "\s*", RegexOptions.IgnoreCase) expr = reConst.Replace(expr, AddressOf DoConstants) Do Until reNum.IsMatch(expr) Dim saveExpr As String = expr Do While rePower.IsMatch(expr) expr = rePower.Replace(expr, AddressOf DoPower) Loop Do While reMulDiv.IsMatch(expr) expr = reMulDiv.Replace(expr, AddressOf DoMulDiv) Loop Do While reFuncN.IsMatch(expr) expr = reFuncN.Replace(expr, AddressOf DoFuncN) Loop Do While reFunc2.IsMatch(expr) expr = reFunc2.Replace(expr, AddressOf DoFunc2) Loop Do While reFunc1.IsMatch(expr) expr = reFunc1.Replace(expr, AddressOf DoFunc1) Loop expr = reSign1.Replace(expr, "$1") expr = reSign2.Replace(expr, "+") Do While reAddSub.IsMatch(expr) expr = reAddSub.Replace(expr, AddressOf DoAddsub) Loop expr = rePar.Replace(expr, "$1") Loop Return CDbl(expr) End Function Function DoConstants(ByVal m As Match) As String Select Case m.Groups(1).Value.ToUpper Case "PI" Return Math.PI.ToString Case "E" Return Math.E.ToString Case Else Return vbNullString End Select End Function Function DoPower(ByVal m As Match) As String Dim n1 As Double = CDbl(m.Groups(1).Value) Dim n2 As Double = CDbl(m.Groups(3).Value) Return (n1 ^ n2).ToString End Function Function DoMulDiv(ByVal m As Match) As String Dim n1 As Double = CDbl(m.Groups(1).Value) Dim n2 As Double = CDbl(m.Groups(3).Value) Select Case m.Groups(2).Value Case "/" Return (n1 / n2).ToString Case "*" Return (n1 * n2).ToString Case Else Return vbNullString End Select End Function Function DoAddsub(ByVal m As Match) As String Dim n1 As Single = CDec(m.Groups(1).Value) Dim n2 As Single = CDec(m.Groups(3).Value) Select Case m.Groups(2).Value Case "+" Return (n1 + n2).ToString Case "-" Return (n1 - n2).ToString Case Else Return vbNullString End Select End Function Function DoFunc1(ByVal m As Match) As String Dim n1 As String = m.Groups(2).Value Select Case m.Groups(1).Value.ToUpper Case "EXP" Return Math.Exp(n1).ToString Case "LOG" Return Math.Log(n1).ToString Case "LOG10" Return Math.Log10(n1).ToString Case "ABS" Return Math.Abs(CDec(n1)).ToString Case "SQR", "SQRT" Return Math.Sqrt(n1).ToString Case "SIN" Return Math.Sin(n1).ToString Case "COS" Return Math.Cos(n1).ToString Case "TAN" Return Math.Tan(n1).ToString Case "ASIN" Return Math.Asin(n1).ToString Case "ACOS" Return Math.Acos(n1).ToString Case "ATAN" Return Math.Atan(n1).ToString Case Else Return vbNullString End Select End Function Function DoFunc2(ByVal m As Match) As String Dim n1 As Double = CDbl(m.Groups(2).Value) Dim n2 As Double = CDbl(m.Groups(3).Value) Select Case m.Groups(1).Value.ToUpper Case "ATAN2" Return Math.Atan2(n1, n2).ToString Case Else Return vbNullString End Select End Function Function DoFuncN(ByVal m As Match) As String Dim args As New ArrayList() Dim i As Integer = 2 Do While m.Groups(i).Value <> "" args.Add(CDbl(m.Groups(i).Value.Replace(","c, " "c))) i += 1 Loop Select Case m.Groups(1).Value.ToUpper Case "MIN" args.Sort() Return args(0).ToString Case "MAX" args.Sort() Return args(args.Count - 1).ToString Case Else Return vbNullString End Select End Function Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click TextBox2.Text = Evaluate(TextBox1.Text) End Sub Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load End SubEnd Class