Hi I am trying to make some code to collect tokens of a string. but I keep getting an out of range error, tho it works with some expressions
here my code.
If you run the code with this expression eveything is fine "8 * 2 + (10+5)"
But if you run it with this you get an out of range error. 8 * 2 + 1
I don't see why cos the first expression has more length than the second.
here my code.
Code:
Public Class Form1
Private Enum Tokypes
None = 0
Digit = 1
Sysmbol = 2
End Enum
'Private Expression As String = "8 * 2 + (10+5)" 'Works fine on this expression.
Private Expression As String = "8 * 2 + 1" ' VB Crys on this one why
Private Pos As Integer = 0
Dim sToken As String = vbNullString
Dim sTokType As Tokypes
Private Function isDelim(ByVal c As Char) As Boolean
If (("+-/*%^=()".IndexOf(c) <> -1)) Then
Return True
End If
Return False
End Function
Private Sub GetTokens()
sToken = vbNullString
sTokType = Tokypes.None
If (Pos = Expression.Length) Then
sToken = vbNullString
sTokType = Tokypes.None
Return
End If
'Skip white
While (Pos < Expression.Length) And Char.IsWhiteSpace(Expression(Pos))
Pos += 1
End While
'
If isDelim(Expression(Pos)) Then
sToken = sToken & Expression(Pos)
Pos += 1
'Token Type.
sTokType = Tokypes.Sysmbol
ElseIf Char.IsDigit(Expression(Pos)) Then
'Thowing error here - Index was outside the bounds of the array.
While Char.IsDigit((Expression(Pos)))
sToken = sToken & Expression(Pos)
Pos += 1
End While
If Pos = Expression.Length Then Return
'Token Type.
sTokType = Tokypes.Digit
End If
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
GetTokens()
While sTokType <> Tokypes.None
MsgBox(sToken)
GetTokens()
End While
End Sub
End ClassBut if you run it with this you get an out of range error. 8 * 2 + 1
I don't see why cos the first expression has more length than the second.