deleting & writing in the same file

[jasie24]

i have a file info.ini

which has a text like:

;comment
[management=1]
patid=34
;following fields not need it
lastname=johnson
firstname=tom

[image]
color=445


the questin is how can i delete or replace the patid=34 with some other patid=2
and
lastname=thomas
firstname=glen

?
i tried to write over spaces,but the problem is that i cannot know exactly when is the end of line,and also the real problem is that end of line,i will have to overwrite
with a much longer line,and it will go over next line,and it will be a mess.
as i noticed ,this writing in a file work like the overwrite,not like the insert ,from the keyboard?

i used something like this:
Dim fs As New FileStream("c:\we.txt", FileMode.OpenOrCreate, FileAccess.Read, FileShare.ReadWrite)
Dim fs1 As New FileStream("C:\we.txt", FileMode.OpenOrCreate, FileAccess.Write, FileShare.ReadWrite)
Dim sr As StreamReader = New StreamReader(fs)
Dim sw As New StreamWriter(fs1)
Dim str As String
Dim allText As String

Do
str = sr.ReadLine()
allText = allText & str

If str = "patid=34" Then
Dim pos As Integer
MessageBox.Show(allText)
pos = allText.Length - str.Length
MessageBox.Show(pos)
fs1.Seek(pos, SeekOrigin.Begin)
sw.Write(Space(20 * 256))
fs1.Seek(pos, SeekOrigin.Begin)

sw.WriteLine("patid=2")
sw.WriteLine(";following fields not need it")
sw.WriteLine("lastname=thomas")
sw.writeline("firstname=glen")
Exit do
End If

Loop Until str Is Nothing
sw.Flush()

sw.Close()

sr.Close()
fs.Close()
MessageBox.Show("end")

so i simulate the deleting,by inserting lots of spaces,but because of that \r\n it will be a mess.beacuse i want to overwrite again other information,with other names,and in file it will be lots of spaces,and that seek() reposition at the end of that file.and all this because the writting is like an overwrite not like an insert,and i'm not able to delete and insert.

[Gizmo001]

Why don't you first open the file for input only, read and store each line in an array of strings. Close the file Change the line you want to change. Then open the file for output and write each line in the same order. Then save the file. Since .ini files are not that large, this should work very well.

[jasie24]

Why don't you first open the file for input only, read and store each line in an array of strings. Close the file Change the line you want to change. Then open the file for output and write each line in the same order. Then save the file. Since .ini files are not that large, this should work very well.

you don't understand that it does not matter when you write in the file,if you close and after that open to write,is the same,the ideea is the writing.if the new line is smaller that old line it will remain the rest of the old line because it will overwrite the string,do you understand that?

try your solution,have a initial file,and replace with a smaller or larger string and you will see that it will be a mess the file after all this.

[Gizmo001]

If what you say is true, then you can try this:

after you have stored the information during file-read, close and delete the file. Then open a new file with the same name and write into that the stored and edited information.

[Gizmo001]

In any case, you are wrong about strings being left over. Whenever you open a file for Output, the file is completely overwritten. Add two buttons and try this code. Check the file after you click button1. The new file will have a long line full of numbers. Check the file after you click the second button. The line has only one letter. The rest is gone. Key is to open the file for "output."



Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fn As Integer
fn = FreeFile()
FileOpen(fn, "C:\Newfile.dat", OpenMode.Output)
Print(fn, "123456789012345678901234567890")
FileClose(fn)
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim fn As Integer
fn = FreeFile()
FileOpen(fn, "C:\Newfile.dat", OpenMode.Output)
Print(fn, "9")
FileClose(fn)
End Sub

[jasie24]

In any case, you are wrong about strings being left over. Whenever you open a file for Output, the file is completely overwritten. Add two buttons and try this code. Check the file after you click button1. The new file will have a long line full of numbers. Check the file after you click the second button. The line has only one letter. The rest is gone. Key is to open the file for "output."



Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fn As Integer
fn = FreeFile()
FileOpen(fn, "C:\Newfile.dat", OpenMode.Output)
Print(fn, "123456789012345678901234567890")
FileClose(fn)
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim fn As Integer
fn = FreeFile()
FileOpen(fn, "C:\Newfile.dat", OpenMode.Output)
Print(fn, "9")
FileClose(fn)
End Sub

i have to convince you,because maybe you don't understand my problem.
rename that newfile.dat as newfile.ini to be able to see what have you written inside the file.
after that ,before start playing with those 2 buttons,put 2-3 lines in that newfile.ini

that's the ideea
to rename some of the lines,not all
so once that you ahve more lines,meanning that you press ENTER inside him(cr+lf)
it will write the new strings over those specials characters,and it will be a mess,it will be erased all the content,actually overwritten.

[Gizmo001]

I did what you told me to. I did not get any mess. Here is one line with all kinds of characters in a ".ini" file. I checked the files after running each button and could see all the characters as they were supposed to be. May be the editor you are using to read the file is the problem. For example, notepad does not show half the characters correctly. But Microsoft Word does. OR Maybe as you point out, I REALLY Don't Get it. If that is the case, I apologize for wasting your time.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If File.Exists("C:\Newfile.ini") Then
File.Delete("C:\Newfile.ini")
End If
fn = FreeFile()
FileOpen(fn, "C:\Newfile.ini", OpenMode.Output)
Print(fn, "!@#$%^&*()!@#$%^&&**((!@#%^*(*&^%$#@#$%^&")
FileClose(fn)
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
fn = FreeFile()
FileOpen(fn, "C:\Newfile.ini", OpenMode.Output)
Print(fn, "^&((")
FileClose(fn)
End Sub

[DeepButi]

jasie24,
as far as I can see you're trying something inconsistent with the basic concept of a sequential file.

To "update" a sequential file you have to create a new one, but trying to overwrite it will never work correctly.

You can "update" a binary file and even then you can not cross logical record boundaries. And of course you can open a text sequential file as a binary one, but you will have to deal with where cr+lf are, not to overwrite them, and so on, so it sounds really out of mind to me.

Open your file, get a line at a time, write it (or the modified one) to a new file and, once done, delete the original file and rename the new one.

Dim InputFile as IO.StreamReader
Dim OutputFile as IO.StreamWriter
Dim TheLine as String

FileCopy("MyIni.ini","BackupIni.ini")

InputFile = New IO.StreamReader("BackupIni.ini", System.Text.Encoding.Default)
OutputFile = New IO.StreamWriter("MyIni.ini", False)

TheLine = InputFile.ReadLine
While Not TheLine Is Nothing
If ...your conditions here... Then
OutputFile.WriteLine(TheLine)
Else
OutputFile.WriteLine("The replaced ine")
End If
TheLine = InputFile.ReadLine
End While
InputFile.Close
OutputFile.Close

'Kill "BackupIni.inI" if you don't want the backup anymore

Hope it helps

[Gizmo001]

Going back to your very first question, I created a file named newfile.ini that has the following 8 lines:

;comment
[management=1]
patid=34
;following fields not need it
lastname=johnson
firstname=tom

[image]
color=445


I use the following declarations common to all procedures.

Dim fn As Integer, a(8) As String
Dim i As Integer

I use the following button to read it:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
fn = FreeFile()
FileOpen(fn, "C:\Newfile.ini", OpenMode.Input)
For i = 0 To 8
a(i) = LineInput(fn)
Next
FileClose(fn)
End Sub

And I use the following button to change and write the new text:

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
fn = FreeFile()
FileOpen(fn, "C:\Newfile.ini", OpenMode.Output)
For i = 0 To 8
If i = 2 Then
a(i) = "patid=2"
ElseIf i = 4 Then
a(i) = "LastName=Thomas"
ElseIf i = 5 Then
a(i) = "FirstName=Glen"
End If
Print(fn, a(i) & vbCrLf)
Next
FileClose(fn)
TextBox1.ForeColor = Color.FromArgb(CInt(Mid(TextBox1.Text, 1, 3)), CInt(Mid(TextBox1.Text, 5, 3)), CInt(Mid(TextBox1.Text, 9, 3)))
End Sub


And I get the following result as you wanted:

;comment
[management=1]
patid=2
;following fields not need it
LastName=Thomas
FirstName=Glen

[image]
color=445


Is this not what you wanted?

[jasie24]

Now finally is working,this new variant is really working,,because,yes this was what i wanted,but it's different from all soutions until now,anyway so i thank you,for you solution and :) also for your persistance.

thanks again.