Programming Forums > Application Development > Visual Basic .NET

Jabo · Oct 4th, 2007, 3:04 AM

I'm trying to make a parser for a text file, but I'm getting an object reference error. Can somebody tell me why?

Dim filereader As String
        Dim parser() As String
        Dim ArrSize, i, j, x As Integer
        Dim word(), newword() As Char

        filereader = My.Computer.FileSystem.ReadAllText("m:\VC++Express\Open Media Distribution List[1].txt")
        parser = Split(filereader)
        ArrSize = parser.Length
        For i = 0 To ArrSize - 1
            word = parser(i).ToCharArray
            x = word.Length
            For j = 0 To x - 1
                If Char.IsLetterOrDigit(word(j)) Then
                    newword(newword.Length) = word(j)
                End If
            Next
            parser(i) = newword.ToString
            lboTSMTape.Items.Add(parser(i))
        Next

The red line has error attached to it saying object reference not set to an instance of an object

melbolt · Oct 4th, 2007, 9:02 AM

let me see if I can explain this right.

here's the problem, you attempt to put something in the array newword but you never allocated any space for that array.

what i mean by this is, you never gave it bounds ex: newword(5) would allocate 5 indexes.

what you can do is this...

 vbnet Syntax (Toggle Plain Text) 
           word = parser(i).ToCharArray
           Dim newword(word.Length) As Char
           word = parser(i).ToCharArray
           Dim newword(word.Length) As Char

the reason you didn't have to set up the word array like this is because you are not trying to utilize its indexes until you set it equal to an existing array(which does have allocated memory)
ex:

 vbnet Syntax (Toggle Plain Text) 
 word = parser(i).ToCharArray
 word = parser(i).ToCharArray

Jabo · Oct 4th, 2007, 9:07 AM

Ahh, that makes a lot of sense, thanks melbolt. But now i'm gonna have to rethink my algorithm because the array will be different each time. Can you dynamically allocate a vector? I need to re-learn how to do a vector.

Jabo · Oct 5th, 2007, 2:37 AM

Here's what I wound up doing; it's not elegant, but it does the job.

(Toggle Plain Text)

Dim filereader As String
        Dim parser() As String
        Dim ArrSize, i, j, x, y As Integer
        Dim word(30), newword(30) As Char

        filereader = My.Computer.FileSystem.ReadAllText(cboFileList.Text)
        parser = Split(filereader)
        ArrSize = parser.Length

        For i = 0 To ArrSize - 1
            word = parser(i).ToCharArray
            x = word.Length
            y = 0
            For j = 0 To 29
                newword(j) = ""
            Next
            For j = 0 To x - 1
                If (Char.IsLetterOrDigit(word(j))) Then
                    newword(y) = word(j)
                    y = y + 1
                End If
            Next
            parser(i) = newword
            If parser(i).Substring(0, 2) = "CD" Or parser(i).Substring(0, 2) = "00" Then
                lboTSMTape.Items.Add(parser(i))
            End If
        Next

Oct 4th, 2007, 3:04 AM	#1
Jabo Not a user? Join Date: Sep 2007 Posts: 245 Rep Power: 1	Object reference error I'm trying to make a parser for a text file, but I'm getting an object reference error. Can somebody tell me why? (Toggle Plain Text) Dim filereader As String Dim parser() As String Dim ArrSize, i, j, x As Integer Dim word(), newword() As Char filereader = My.Computer.FileSystem.ReadAllText("m:\VC++Express\Open Media Distribution List[1].txt") parser = Split(filereader) ArrSize = parser.Length For i = 0 To ArrSize - 1 word = parser(i).ToCharArray x = word.Length For j = 0 To x - 1 If Char.IsLetterOrDigit(word(j)) Then newword(newword.Length) = word(j) End If Next parser(i) = newword.ToString lboTSMTape.Items.Add(parser(i)) Next Dim filereader As String Dim parser() As String Dim ArrSize, i, j, x As Integer Dim word(), newword() As Char filereader = My.Computer.FileSystem.ReadAllText("m:\VC++Express\Open Media Distribution List[1].txt") parser = Split(filereader) ArrSize = parser.Length For i = 0 To ArrSize - 1 word = parser(i).ToCharArray x = word.Length For j = 0 To x - 1 If Char.IsLetterOrDigit(word(j)) Then newword(newword.Length) = word(j) End If Next parser(i) = newword.ToString lboTSMTape.Items.Add(parser(i)) Next The red line has error attached to it saying object reference not set to an instance of an object

Oct 4th, 2007, 9:02 AM	#2
melbolt Hobbyist Programmer Join Date: Feb 2005 Location: PA, USA Posts: 233 Rep Power: 4	let me see if I can explain this right. here's the problem, you attempt to put something in the array newword but you never allocated any space for that array. what i mean by this is, you never gave it bounds ex: newword(5) would allocate 5 indexes. what you can do is this... vbnet Syntax (Toggle Plain Text) word = parser(i).ToCharArray Dim newword(word.Length) As Char word = parser(i).ToCharArray Dim newword(word.Length) As Char the reason you didn't have to set up the word array like this is because you are not trying to utilize its indexes until you set it equal to an existing array(which does have allocated memory) ex: vbnet Syntax (Toggle Plain Text) word = parser(i).ToCharArray word = parser(i).ToCharArray __________________ I have never let my schooling interfere with my education. -Mark Twain- Xbox live gamertag: melbolt

Oct 5th, 2007, 2:37 AM	#4
Jabo Not a user? Join Date: Sep 2007 Posts: 245 Rep Power: 1	Here's what I wound up doing; it's not elegant, but it does the job. (Toggle Plain Text) Dim filereader As String Dim parser() As String Dim ArrSize, i, j, x, y As Integer Dim word(30), newword(30) As Char filereader = My.Computer.FileSystem.ReadAllText(cboFileList.Text) parser = Split(filereader) ArrSize = parser.Length For i = 0 To ArrSize - 1 word = parser(i).ToCharArray x = word.Length y = 0 For j = 0 To 29 newword(j) = "" Next For j = 0 To x - 1 If (Char.IsLetterOrDigit(word(j))) Then newword(y) = word(j) y = y + 1 End If Next parser(i) = newword If parser(i).Substring(0, 2) = "CD" Or parser(i).Substring(0, 2) = "00" Then lboTSMTape.Items.Add(parser(i)) End If Next Dim filereader As String Dim parser() As String Dim ArrSize, i, j, x, y As Integer Dim word(30), newword(30) As Char filereader = My.Computer.FileSystem.ReadAllText(cboFileList.Text) parser = Split(filereader) ArrSize = parser.Length For i = 0 To ArrSize - 1 word = parser(i).ToCharArray x = word.Length y = 0 For j = 0 To 29 newword(j) = "" Next For j = 0 To x - 1 If (Char.IsLetterOrDigit(word(j))) Then newword(y) = word(j) y = y + 1 End If Next parser(i) = newword If parser(i).Substring(0, 2) = "CD" Or parser(i).Substring(0, 2) = "00" Then lboTSMTape.Items.Add(parser(i)) End If Next

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Oct 4th, 2007, 9:07 AM	#3
Jabo Not a user? Join Date: Sep 2007 Posts: 245 Rep Power: 1	Ahh, that makes a lot of sense, thanks melbolt. But now i'm gonna have to rethink my algorithm because the array will be different each time. Can you dynamically allocate a vector? I need to re-learn how to do a vector.

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Programming Forums > Application Development > Visual Basic .NET

Object reference error