Add/Remove to/from File

[PureSc0pe]

The first code writes the text to the end line, but if used more than once, it puts all of the added text on the same line. How do I make it write to its own line every time?

 

Also, how can the second code be used to delete a line of text. I want to have to type the exact line that you want deleted for it to work.

 

VB Code: Add to File

 

Dim file As String

Dim StreamWriter As New IO.StreamWriter(TextBox2.Text, True)

StreamWriter.Write(TextBox3.Text)

StreamWriter.Close()

 

 

VB Code: Delete from File

 

Dim file As String

Dim StreamWriter As New IO.StreamWriter(TextBox2.Text)

StreamWriter.Write(TextBox4.Text)

StreamWriter.Close()

[TechnoTone]

See WriteLine.

[Iceplug]

With Sequential File Access streams, you don't actually "delete" a line from a file.

You just "conveniently forget to put it back in the file".

 

You'd want to have a Stream for Reading and then one for Writing.

You can use a StringBuilder also. (something like this)

Caption = SR.Readline()
[color=Teal]'Read a line from file.[/color]
[color=Blue]If[/color] Caption <> "asdfghjkl" [color=Blue]Then[/color]
 SB.Append(Caption)
 SB.Append(System.Environment.NewLine)
[color=Teal]'Conveniently forget to write the line "asdfghjkl" back to file.[/color]
[color=Blue]End If
Loop[/color]
SW.Write(SB.ToString())
[color=Teal]'Write the built string to file.[/color]

[PureSc0pe]

I've got most of what you've said here, but SB? I assume that is Stringbuilder as you mentioned earlier. However, StringBuilder is not showing up as a Variable or whatever. Anything in Bold has an error.

 

VB Code:

 

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

Dim file As String

Dim SR As New IO.StreamReader(TextBox2.Text)

Dim SW As New IO.StreamWriter(TextBox2.Text)

Dim SB As StringBuilder

 

file = (TextBox2.Text)

file = SR.ReadLine()

 

If file <> (TextBox4.Text) Then

SB.Append(file)

SB.Append(System.Environment.NewLine)

 

End If

Loop

SW.Write(SB.ToString())

 

End Sub

Edited March 26, 2004 by PureSc0pe

[Iceplug]

[color=Blue]Dim[/color] SB [color=Blue]As[/color] System.Text.StringBuilder = [color=Blue]New[/color] System.Text.StringBuilder()

[PureSc0pe]

The Code shows no errors, but when I run the application it says:

An unhandled exception of type 'System.IO.IOException' occurred in mscorlib.dll. Additional information: The process cannot access the file "C:\list.txt" because it is being used by another process.

It highlights Dim SW As New IO.StreamWriter(TextBox2.text) as the problem. Is it saying that because it's being used by StreamReader? If so, how would I fix that?

 

 

VB Code:

 

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

Dim file As String

Dim SR As New IO.StreamReader(TextBox2.Text)

Dim SW As New IO.StreamWriter(TextBox2.Text)

Dim SB As System.Text.StringBuilder = New System.Text.StringBuilder

 

file = (TextBox2.Text)

file = SR.ReadLine()

 

If file <> (TextBox4.Text) Then

SB.Append(file)

SB.Append(System.Environment.NewLine)

 

End If

SW.Write(SB.ToString())

 

End Sub

[Iceplug]

Oh, yeah, you need to close the streamreader before you can open the streamwriter.

So, your code will look something like this.

Dim SR As IO.StreamReader = New StreamReader(...)

Dim SW As IO.StreamWriter

 

SR.Close()

SW = New StreamWriter(...)

SW.Write(...)

SW.Close()

[PureSc0pe]

Ok, when I run it, it deletes everything from the file except the first line. I need it to keep everything except what is typed into the texbox.

 

VB Code:

 

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

Dim file As String

Dim SR As New IO.StreamReader(TextBox2.Text)

 

file = (TextBox2.Text)

file = SR.ReadLine()

 

SR.Close()

 

Dim SW As New IO.StreamWriter(TextBox2.Text)

Dim SB As System.Text.StringBuilder = New System.Text.StringBuilder

 

If file <> (TextBox4.Text) Then

SB.Append(file)

SB.Append(System.Environment.NewLine)

End If

 

SW.Write(SB.ToString())

 

SW.Close()

End Sub

[AFterlife]

:D PureScope is going to be the Master of File I/O! :D

[PureSc0pe]

:D PureScope is going to be the Master of File I/O! :D

 

 

:D Hope so, but for now I still need help on what I said in my last post.

[PlausiblyDamp]

You are opening your streamreader (SR) but then closing it after only 1 Readline. you would really need to do this in a loop. Try something like the following (not tested though so no promises)

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click

	Dim line As String = ""

	Dim SR As New IO.StreamReader(TextBox2.Text)

	Dim SB As System.Text.StringBuilder = New System.Text.StringBuilder
	Do
		line = SR.ReadLine
		If line <> TextBox4.Text Then
			SB.Append(line)
			SB.Append(System.Environment.NewLine)
		End If
	Loop Until line = ""
	SR.Close()

	Dim SW As New IO.StreamWriter(TextBox2.Text, False)

	SW.Write(SB.ToString())
	SW.Close()

End Sub

[PureSc0pe]

That worked great, thanks for all your help. :D