How do I append text to a text file, over writing a specific line,

Posted on 2006-06-25
Medium Priority
Last Modified: 2010-04-07

I need tobe able to write a line to a text file overwriting the third line. I have used append but this just adds a line at the bottom of the file rather then over a specific line. I am using

Open file For Append As #1

Print #1, value

Close #1
Question by:eneate
  • 3
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LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 16978938
>I need tobe able to write a line to a text file overwriting the third line.
you have to read the entire file, and replace the third line by the new contents.

only if all the lines have EXACTLY the same width you could open the file in binary mode, go to the specific record, and put the new contents.

in your case, I would copy the file first (to .bak), then rewrite the file using code like this:

dim intInput as integer
dim intOutput as integer
dim intLine as integer
dim strLine as string

intInput = FreeFile()
intOutput = FreeFile()

open "file.bak" for input as #intInput
open "file.dat" for output as #intOutput

while not eof(intInput)
  line input #intInput, strLine
  intLine = intLine + 1

  if intLine = 3 then
     print #intOutput, Value
     print #intOutput, strLine
  end if

close #intInput
clost #intOutput


Author Comment

ID: 16979047

How would I write the code to open the file and re save it as a new name, sorry this sounds really simple but I just can't quite find the right combination
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 16979055
FileCopy "file.dat" ,"file.bak"
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Author Comment

ID: 16979210

I've tried the following

Dim intInput As Integer
Dim intOutput As Integer
Dim intLine As Integer
Dim strLine As String
Const dcs_file As String = "c:\ipwin5\DCS-3.ini"
Dim value As String
value = "Veridata value: 0"

intInput = FreeFile()
intOutput = FreeFile()

If FileExists(dcs_file) Then

FileCopy "c:\ipwin5\DCS-3.ini", "c:\ipwin5\DCS-3.bak"

Open "c:\ipwin5\DCS-3.bak" For Input As #intInput
'Open "c:\ipwin5\DCS-3.ini" For Output As #intOutput    I've tried commenting this out as I get file already open.

While Not EOF(intInput)
  Line Input #intInput, strLine
  intLine = intLine + 1

  If intLine = 3 Then
     Print #intOutput, value
     Print #intOutput, strLine
  End If

Close #intInput
Close #intOutput

End If

As noted as bove I get file already open,if I comment it out at line print #output,strline I get error 54
bad file mode

Any ideas - thanks for the input.
LVL 143

Accepted Solution

Guy Hengel [angelIII / a3] earned 1000 total points
ID: 16979422
>'Open "c:\ipwin5\DCS-3.ini" For Output As #intOutput    I've tried commenting this out as I get file already open.
well, then you have some other process locking the file.
if another process locks the file, you cannot write to it. no way.

Author Comment

ID: 16979432
That's ok I've found another way round it, but thanks for the feedback. I;ll sort the points.

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