如:
dim a as interger,b as interger,c as string
a=1
b=2
c="a+b"
msgbox 『』
现在我想通过我事先存储在变量c中的表达式,并且计算它,最后得到结果3.
dim a as interger,b as interger,c as string
a=1
b=2
c="a+b"
msgbox 『』
现在我想通过我事先存储在变量c中的表达式,并且计算它,最后得到结果3.
a=1
b=2
c=a + b
msgbox c
'这样是可以实现你的想法但是如果按照你的所想,把字符串表达式变成数学表达式
然后再算出它的值,那就比较麻烦,首先没有直接转换的
方法,想实现只有通过你的算法对字符串加以判断分解然
后再算出它的值。
比如dim x as integer
dim y as string
x=10
y="10"
'再c++中这样的转换比VB要复杂,搞清楚对你很有帮助
Dim a As Integer, b As Integer, c As String
a = 1
b = 2
c = "a+b"
x = Split(c, "+")
x(0) = a
x(1) = b
MsgBox Val(x(0)) + Val(x(1))End Sub
Dim i, n As Integer
Dim TempGs, Temp As String
Dim Vl() As String '操作数
Dim Vls As Integer '操作数的数目
Dim Si As Integer '上一操作符的位置
Dim Ads, Sus, Mus, Bys, Lks, Rks As Integer '操作符的数目
Dim Adp(), Mup(), Byp(), Lkp(), Rkp() As Integer '操作符的位置
Dim Adn(), Mun(), Byn() As Integer '操作符的排列次序
Dim Sig() As Integer '每一个操作符的位置 On Error GoTo Err
Do While True
ReDim Adp(Len(GS)), Mup(Len(GS)), Byp(Len(GS)), Lkp(Len(GS)), Rkp(Len(GS)) As Integer
ReDim Adn(Len(GS)), Mun(Len(GS)), Byn(Len(GS)), Lkn(Len(GS)), Rkn(Len(GS)), Sig(Len(GS)) As Integer
ReDim Vl(Len(GS))
If Len(GS) = 0 Then GoTo Err
If Mid(GS, Len(GS), 1) <> "#" Then
TempGs = GS
For i = 1 To Len(GS) '将减化加
If Mid(GS, i, 1) = "-" And i <> 1 Then
If Mid(GS, i - 1, 1) <> "+" And Mid(GS, i - 1, 1) <> "-" _
And Mid(GS, i - 1, 1) <> "*" And Mid(GS, i - 1, 1) <> "/" Then
TempGs = Mid(TempGs, 1, i - 1 + n) + "+" + Mid(GS, i)
n = n + 1
End If
End If
Next i
GS = TempGs
n = 0
For i = 1 To Len(GS) '处理负负得正
If Mid(GS, i, 1) = "-" Then
If Mid(GS, i + 1, 1) = "-" Then
TempGs = Mid(TempGs, 1, i - 1 - n) + Mid(GS, i + 2)
n = n + 2
End If
End If
Next i
GS = TempGs
GS = GS + "#"
End If
Vls = 1
Ads = 0: Sus = 0: Mus = 0: Bys = 0: Lks = 0: Rks = 0
For i = 1 To Len(GS)
Select Case Mid(GS, i, 1)
Case "+"
Ads = Ads + 1
Adp(Ads) = i
Adn(Ads) = Vls
Case "*"
Mus = Mus + 1
Mup(Mus) = i
Mun(Mus) = Vls
Case "/"
Bys = Bys + 1
Byp(Bys) = i
Byn(Bys) = Vls
Case "("
Lks = Lks + 1
Lkp(Lks) = i
Case ")"
Rks = Rks + 1
Rkp(Rks) = i
End Select
If Mid(GS, i, 1) = "+" Or Mid(GS, i, 1) = "*" Or Mid(GS, i, 1) = "/" Or Mid(GS, i, 1) = "#" Then
If Si + 1 = i And Mid(GS, i + 1, 1) <> "#" Then '操作符非法连续或以操作符开头
GoTo Err
Else
Si = i
End If
If Not IsNumeric(Vl(Vls)) And Mid(GS, i + 1, 1) <> "#" Then '操作数不是数字
GoTo Err
End If
Sig(Vls) = i
Vls = Vls + 1
Else
If Mid(GS, i, 1) <> "(" And Mid(GS, i, 1) <> ")" Then
Vl(Vls) = Vl(Vls) + Mid(GS, i, 1) '制作操作数
Else
If i <> 1 Then
If ((Mid(GS, i - 1, 1) = "(" And Mid(GS, i, 1) = ")") Or _
(Mid(GS, i - 1, 1) = ")" And Mid(GS, i, 1) = "(")) _
Then '判定括号前后符号的合法性
GoTo Err
End If
End If
End If
End If
Next i
If Lks <> Rks Then
GoTo Err '左右括号数是否匹配
End If
For i = 1 To Lks
If Lkp(i) > Rkp(i) Then GoTo Err '左右括号出现顺序错误
Next i
If Lks <> 0 Then '括号处理
Do While True
For i = Lks To 1 Step -1
For n = Rks To 1 Step -1
Temp = calu(Mid(GS, Lkp(i) + 1, Rkp(n) - Lkp(i) - 1))
If Temp <> "公式有错误" Then
GS = Mid(GS, 1, Lkp(i) - 1) + Temp + Mid(GS, Rkp(n) + 1)
Exit Do
End If
Next n
Next i
If Temp = "公式有错误" Then GoTo Err
'括号中有错误退出
Loop
Else
If Mus <> 0 Then '乘法处理
GS = Mid(GS, 1, Sig(Mun(1) - 1)) + Trim(Str(Val(Vl(Mun(1))) _
* Val(Vl(Mun(1) + 1)))) + Mid(GS, Val(Mup(1)) + Len(Vl(Mun(1) _
+ 1)) + 1)
Else
If Bys <> 0 Then '除法处理
GS = Mid(GS, 1, Sig(Byn(1) - 1)) + Trim(Str(Val(Vl(Byn(1))) _
/ Val(Vl(Byn(1) + 1)))) + Mid(GS, Val(Byp(1)) + Len(Vl(Byn(1) _
+ 1)) + 1)
Else
If Ads <> 0 Then '加法处理
GS = Trim(Str(Val(Vl(1)) + Val(Vl(2)))) + Mid(GS, Val(Adp(1)) _
+ Len(Vl(2)) + 1)
Else
calu = Mid(GS, 1, Len(GS) - 1)
Exit Function
End If
End If
End If
End If
Loop
Err:
calu = "公式有错误"
End Function
Private Sub Command1_Click()
Dim a As Long, b As Long, c As String
a = 1
b = 2
c = a + b '此处想是什么表达式都可以
'c = a + b + b + a + b
MsgBox calu(c)
End Sub
Dim i, n As Integer
Dim TempGs, Temp As String
Dim Vl() As String '操作数
Dim Vls As Integer '操作数的数目
Dim Si As Integer '上一操作符的位置
Dim Ads, Sus, Mus, Bys, Lks, Rks As Integer '操作符的数目
Dim Adp(), Mup(), Byp(), Lkp(), Rkp() As Integer '操作符的位置
Dim Adn(), Mun(), Byn() As Integer '操作符的排列次序
Dim Sig() As Integer '每一个操作符的位置 On Error GoTo Err
Do While True
ReDim Adp(Len(GS)), Mup(Len(GS)), Byp(Len(GS)), Lkp(Len(GS)), Rkp(Len(GS)) As Integer
ReDim Adn(Len(GS)), Mun(Len(GS)), Byn(Len(GS)), Lkn(Len(GS)), Rkn(Len(GS)), Sig(Len(GS)) As Integer
ReDim Vl(Len(GS))
If Len(GS) = 0 Then GoTo Err
If Mid(GS, Len(GS), 1) <> "#" Then
TempGs = GS
For i = 1 To Len(GS) '将减化加
If Mid(GS, i, 1) = "-" And i <> 1 Then
If Mid(GS, i - 1, 1) <> "+" And Mid(GS, i - 1, 1) <> "-" _
And Mid(GS, i - 1, 1) <> "*" And Mid(GS, i - 1, 1) <> "/" Then
TempGs = Mid(TempGs, 1, i - 1 + n) + "+" + Mid(GS, i)
n = n + 1
End If
End If
Next i
GS = TempGs
n = 0
For i = 1 To Len(GS) '处理负负得正
If Mid(GS, i, 1) = "-" Then
If Mid(GS, i + 1, 1) = "-" Then
TempGs = Mid(TempGs, 1, i - 1 - n) + Mid(GS, i + 2)
n = n + 2
End If
End If
Next i
GS = TempGs
GS = GS + "#"
End If
Vls = 1
Ads = 0: Sus = 0: Mus = 0: Bys = 0: Lks = 0: Rks = 0
For i = 1 To Len(GS)
Select Case Mid(GS, i, 1)
Case "+"
Ads = Ads + 1
Adp(Ads) = i
Adn(Ads) = Vls
Case "*"
Mus = Mus + 1
Mup(Mus) = i
Mun(Mus) = Vls
Case "/"
Bys = Bys + 1
Byp(Bys) = i
Byn(Bys) = Vls
Case "("
Lks = Lks + 1
Lkp(Lks) = i
Case ")"
Rks = Rks + 1
Rkp(Rks) = i
End Select
If Mid(GS, i, 1) = "+" Or Mid(GS, i, 1) = "*" Or Mid(GS, i, 1) = "/" Or Mid(GS, i, 1) = "#" Then
If Si + 1 = i And Mid(GS, i + 1, 1) <> "#" Then '操作符非法连续或以操作符开头
GoTo Err
Else
Si = i
End If
If Not IsNumeric(Vl(Vls)) And Mid(GS, i + 1, 1) <> "#" Then '操作数不是数字
GoTo Err
End If
Sig(Vls) = i
Vls = Vls + 1
Else
If Mid(GS, i, 1) <> "(" And Mid(GS, i, 1) <> ")" Then
Vl(Vls) = Vl(Vls) + Mid(GS, i, 1) '制作操作数
Else
If i <> 1 Then
If ((Mid(GS, i - 1, 1) = "(" And Mid(GS, i, 1) = ")") Or _
(Mid(GS, i - 1, 1) = ")" And Mid(GS, i, 1) = "(")) _
Then '判定括号前后符号的合法性
GoTo Err
End If
End If
End If
End If
Next i
If Lks <> Rks Then
GoTo Err '左右括号数是否匹配
End If
For i = 1 To Lks
If Lkp(i) > Rkp(i) Then GoTo Err '左右括号出现顺序错误
Next i
If Lks <> 0 Then '括号处理
Do While True
For i = Lks To 1 Step -1
For n = Rks To 1 Step -1
Temp = calu(Mid(GS, Lkp(i) + 1, Rkp(n) - Lkp(i) - 1))
If Temp <> "公式有错误" Then
GS = Mid(GS, 1, Lkp(i) - 1) + Temp + Mid(GS, Rkp(n) + 1)
Exit Do
End If
Next n
Next i
If Temp = "公式有错误" Then GoTo Err
'括号中有错误退出
Loop
Else
If Mus <> 0 Then '乘法处理
GS = Mid(GS, 1, Sig(Mun(1) - 1)) + Trim(Str(Val(Vl(Mun(1))) _
* Val(Vl(Mun(1) + 1)))) + Mid(GS, Val(Mup(1)) + Len(Vl(Mun(1) _
+ 1)) + 1)
Else
If Bys <> 0 Then '除法处理
GS = Mid(GS, 1, Sig(Byn(1) - 1)) + Trim(Str(Val(Vl(Byn(1))) _
/ Val(Vl(Byn(1) + 1)))) + Mid(GS, Val(Byp(1)) + Len(Vl(Byn(1) _
+ 1)) + 1)
Else
If Ads <> 0 Then '加法处理
GS = Trim(Str(Val(Vl(1)) + Val(Vl(2)))) + Mid(GS, Val(Adp(1)) _
+ Len(Vl(2)) + 1)
Else
calu = Mid(GS, 1, Len(GS) - 1)
Exit Function
End If
End If
End If
End If
Loop
Err:
calu = "公式有错误"
End Function
Private Sub Command1_Click()
Dim a As Long, b As Long
a = 1
b = 2 MsgBox calu(a + b) '此处想是什么表达式都可以
MsgBox calu((a + b) + b + (a + 3) * b)
End Sub
'纠正了10楼的错误, 拷贝即可使用Public Function calu(GS As String) As String
Dim i, n As Integer
Dim TempGs, Temp As String
Dim Vl() As String '操作数
Dim Vls As Integer '操作数的数目
Dim Si As Integer '上一操作符的位置
Dim Ads, Sus, Mus, Bys, Lks, Rks As Integer '操作符的数目
Dim Adp(), Mup(), Byp(), Lkp(), Rkp() As Integer '操作符的位置
Dim Adn(), Mun(), Byn() As Integer '操作符的排列次序
Dim Sig() As Integer '每一个操作符的位置 On Error GoTo Err
Do While True
ReDim Adp(Len(GS)), Mup(Len(GS)), Byp(Len(GS)), Lkp(Len(GS)), Rkp(Len(GS)) As Integer
ReDim Adn(Len(GS)), Mun(Len(GS)), Byn(Len(GS)), Lkn(Len(GS)), Rkn(Len(GS)), Sig(Len(GS)) As Integer
ReDim Vl(Len(GS))
If Len(GS) = 0 Then GoTo Err
If Mid(GS, Len(GS), 1) <> "#" Then
TempGs = GS
For i = 1 To Len(GS) '将减化加
If Mid(GS, i, 1) = "-" And i <> 1 Then
If Mid(GS, i - 1, 1) <> "+" And Mid(GS, i - 1, 1) <> "-" _
And Mid(GS, i - 1, 1) <> "*" And Mid(GS, i - 1, 1) <> "/" Then
TempGs = Mid(TempGs, 1, i - 1 + n) + "+" + Mid(GS, i)
n = n + 1
End If
End If
Next i
GS = TempGs
n = 0
For i = 1 To Len(GS) '处理负负得正
If Mid(GS, i, 1) = "-" Then
If Mid(GS, i + 1, 1) = "-" Then
TempGs = Mid(TempGs, 1, i - 1 - n) + Mid(GS, i + 2)
n = n + 2
End If
End If
Next i
GS = TempGs
GS = GS + "#"
End If
Vls = 1
Ads = 0: Sus = 0: Mus = 0: Bys = 0: Lks = 0: Rks = 0
For i = 1 To Len(GS)
Select Case Mid(GS, i, 1)
Case "+"
Ads = Ads + 1
Adp(Ads) = i
Adn(Ads) = Vls
Case "*"
Mus = Mus + 1
Mup(Mus) = i
Mun(Mus) = Vls
Case "/"
Bys = Bys + 1
Byp(Bys) = i
Byn(Bys) = Vls
Case "("
Lks = Lks + 1
Lkp(Lks) = i
Case ")"
Rks = Rks + 1
Rkp(Rks) = i
End Select
If Mid(GS, i, 1) = "+" Or Mid(GS, i, 1) = "*" Or Mid(GS, i, 1) = "/" Or Mid(GS, i, 1) = "#" Then
If Si + 1 = i And Mid(GS, i + 1, 1) <> "#" Then '操作符非法连续或以操作符开头
GoTo Err
Else
Si = i
End If
If Not IsNumeric(Vl(Vls)) And Mid(GS, i + 1, 1) <> "#" Then '操作数不是数字
GoTo Err
End If
Sig(Vls) = i
Vls = Vls + 1
Else
If Mid(GS, i, 1) <> "(" And Mid(GS, i, 1) <> ")" Then
Vl(Vls) = Vl(Vls) + Mid(GS, i, 1) '制作操作数
Else
If i <> 1 Then
If ((Mid(GS, i - 1, 1) = "(" And Mid(GS, i, 1) = ")") Or _
(Mid(GS, i - 1, 1) = ")" And Mid(GS, i, 1) = "(")) _
Then '判定括号前后符号的合法性
GoTo Err
End If
End If
End If
End If
Next i
If Lks <> Rks Then
GoTo Err '左右括号数是否匹配
End If
For i = 1 To Lks
If Lkp(i) > Rkp(i) Then GoTo Err '左右括号出现顺序错误
Next i
If Lks <> 0 Then '括号处理
Do While True
For i = Lks To 1 Step -1
For n = Rks To 1 Step -1
Temp = calu(Mid(GS, Lkp(i) + 1, Rkp(n) - Lkp(i) - 1))
If Temp <> "公式有错误" Then
GS = Mid(GS, 1, Lkp(i) - 1) + Temp + Mid(GS, Rkp(n) + 1)
Exit Do
End If
Next n
Next i
If Temp = "公式有错误" Then GoTo Err
'括号中有错误退出
Loop
Else
If Mus <> 0 Then '乘法处理
GS = Mid(GS, 1, Sig(Mun(1) - 1)) + Trim(Str(Val(Vl(Mun(1))) _
* Val(Vl(Mun(1) + 1)))) + Mid(GS, Val(Mup(1)) + Len(Vl(Mun(1) _
+ 1)) + 1)
Else
If Bys <> 0 Then '除法处理
GS = Mid(GS, 1, Sig(Byn(1) - 1)) + Trim(Str(Val(Vl(Byn(1))) _
/ Val(Vl(Byn(1) + 1)))) + Mid(GS, Val(Byp(1)) + Len(Vl(Byn(1) _
+ 1)) + 1)
Else
If Ads <> 0 Then '加法处理
GS = Trim(Str(Val(Vl(1)) + Val(Vl(2)))) + Mid(GS, Val(Adp(1)) _
+ Len(Vl(2)) + 1)
Else
calu = Mid(GS, 1, Len(GS) - 1)
Exit Function
End If
End If
End If
End If
Loop
Err:
calu = "公式有错误"
End Function
Private Sub Command1_Click()
Dim c As String
'c = "2+3"
c = "(2+3)+4+(2+3)*5"
MsgBox calu(c) '此处想是什么表达式都可以,但必须是数值表达式(相当于一个多功能的计算器)
End Sub
'纠正了10楼的错误, 拷贝即可使用Public Function calu(GS As String) As String
Dim i, n As Integer
Dim TempGs, Temp As String
Dim Vl() As String '操作数
Dim Vls As Integer '操作数的数目
Dim Si As Integer '上一操作符的位置
Dim Ads, Sus, Mus, Bys, Lks, Rks As Integer '操作符的数目
Dim Adp(), Mup(), Byp(), Lkp(), Rkp() As Integer '操作符的位置
Dim Adn(), Mun(), Byn() As Integer '操作符的排列次序
Dim Sig() As Integer '每一个操作符的位置 On Error GoTo Err
Do While True
ReDim Adp(Len(GS)), Mup(Len(GS)), Byp(Len(GS)), Lkp(Len(GS)), Rkp(Len(GS)) As Integer
ReDim Adn(Len(GS)), Mun(Len(GS)), Byn(Len(GS)), Lkn(Len(GS)), Rkn(Len(GS)), Sig(Len(GS)) As Integer
ReDim Vl(Len(GS))
If Len(GS) = 0 Then GoTo Err
If Mid(GS, Len(GS), 1) <> "#" Then
TempGs = GS
For i = 1 To Len(GS) '将减化加
If Mid(GS, i, 1) = "-" And i <> 1 Then
If Mid(GS, i - 1, 1) <> "+" And Mid(GS, i - 1, 1) <> "-" _
And Mid(GS, i - 1, 1) <> "*" And Mid(GS, i - 1, 1) <> "/" Then
TempGs = Mid(TempGs, 1, i - 1 + n) + "+" + Mid(GS, i)
n = n + 1
End If
End If
Next i
GS = TempGs
n = 0
For i = 1 To Len(GS) '处理负负得正
If Mid(GS, i, 1) = "-" Then
If Mid(GS, i + 1, 1) = "-" Then
TempGs = Mid(TempGs, 1, i - 1 - n) + Mid(GS, i + 2)
n = n + 2
End If
End If
Next i
GS = TempGs
GS = GS + "#"
End If
Vls = 1
Ads = 0: Sus = 0: Mus = 0: Bys = 0: Lks = 0: Rks = 0
For i = 1 To Len(GS)
Select Case Mid(GS, i, 1)
Case "+"
Ads = Ads + 1
Adp(Ads) = i
Adn(Ads) = Vls
Case "*"
Mus = Mus + 1
Mup(Mus) = i
Mun(Mus) = Vls
Case "/"
Bys = Bys + 1
Byp(Bys) = i
Byn(Bys) = Vls
Case "("
Lks = Lks + 1
Lkp(Lks) = i
Case ")"
Rks = Rks + 1
Rkp(Rks) = i
End Select
If Mid(GS, i, 1) = "+" Or Mid(GS, i, 1) = "*" Or Mid(GS, i, 1) = "/" Or Mid(GS, i, 1) = "#" Then
If Si + 1 = i And Mid(GS, i + 1, 1) <> "#" Then '操作符非法连续或以操作符开头
GoTo Err
Else
Si = i
End If
If Not IsNumeric(Vl(Vls)) And Mid(GS, i + 1, 1) <> "#" Then '操作数不是数字
GoTo Err
End If
Sig(Vls) = i
Vls = Vls + 1
Else
If Mid(GS, i, 1) <> "(" And Mid(GS, i, 1) <> ")" Then
Vl(Vls) = Vl(Vls) + Mid(GS, i, 1) '制作操作数
Else
If i <> 1 Then
If ((Mid(GS, i - 1, 1) = "(" And Mid(GS, i, 1) = ")") Or _
(Mid(GS, i - 1, 1) = ")" And Mid(GS, i, 1) = "(")) _
Then '判定括号前后符号的合法性
GoTo Err
End If
End If
End If
End If
Next i
If Lks <> Rks Then
GoTo Err '左右括号数是否匹配
End If
For i = 1 To Lks
If Lkp(i) > Rkp(i) Then GoTo Err '左右括号出现顺序错误
Next i
If Lks <> 0 Then '括号处理
Do While True
For i = Lks To 1 Step -1
For n = Rks To 1 Step -1
Temp = calu(Mid(GS, Lkp(i) + 1, Rkp(n) - Lkp(i) - 1))
If Temp <> "公式有错误" Then
GS = Mid(GS, 1, Lkp(i) - 1) + Temp + Mid(GS, Rkp(n) + 1)
Exit Do
End If
Next n
Next i
If Temp = "公式有错误" Then GoTo Err
'括号中有错误退出
Loop
Else
If Mus <> 0 Then '乘法处理
GS = Mid(GS, 1, Sig(Mun(1) - 1)) + Trim(Str(Val(Vl(Mun(1))) _
* Val(Vl(Mun(1) + 1)))) + Mid(GS, Val(Mup(1)) + Len(Vl(Mun(1) _
+ 1)) + 1)
Else
If Bys <> 0 Then '除法处理
GS = Mid(GS, 1, Sig(Byn(1) - 1)) + Trim(Str(Val(Vl(Byn(1))) _
/ Val(Vl(Byn(1) + 1)))) + Mid(GS, Val(Byp(1)) + Len(Vl(Byn(1) _
+ 1)) + 1)
Else
If Ads <> 0 Then '加法处理
GS = Trim(Str(Val(Vl(1)) + Val(Vl(2)))) + Mid(GS, Val(Adp(1)) _
+ Len(Vl(2)) + 1)
Else
calu = Mid(GS, 1, Len(GS) - 1)
Exit Function
End If
End If
End If
End If
Loop
Err:
calu = "公式有错误"
End Function
Private Sub Command1_Click()
Dim c As String
'c = "2+3"
c = "(2+3)+4+(2+3)*5"
MsgBox calu(c) '此处想是什么表达式都可以,但必须是数值表达式(相当于一个多功能的计算器)
End Sub
Dim c As String
'c = "2+3"
c = "(2+3)+4+(2+3)*5"
MsgBox calu(c) '此处想是什么表达式都可以,但必须是数值表达式(相当于一个多功能的计算器)
End Sub
这时数据库中的公式便为:"被处罚人资料" & name & "," & sex & "," & birthday & ”,“ & address & "。"
如果公式变为::"被处罚人资料" & name & "," & sex & "," & birthday & ”。" 则得到的语句变为 :被处罚资料:张三,男,1981年01月01日生。但是,我从数据库中提出规则:::"被处罚人资料" & name & "," & sex & "," & birthday & ”。" ,但是没办法把他变成一个有效的vb表达式来执行