Random Access Files

[Alan Roberts]

In VB6 I could use random access and fixed record lengths to read specific
records from a test file. Eg the following code would save a LogEntry to a
file at the location specified by RecordNumber.

Private Type LogEntry
Date As String * 20
Number As String * 20
Source As String * 100
Description As String * 100
CRLF As String * 2
End Type
Public Sub RecordError(Num As Long, Source As String, Desc As String)
Dim FF As Integer
Dim CurrentRecord As LogEntry
'set the record values
With CurrentRecord
.Date = Trim(Format$(No w, "DD/MM/YYYY HH:MM:SS"))
.Number = Num
.Source = Trim(Source)
.Description = Trim(Desc)
.CRLF = vbCrLf
End With
'save the record
FF = FreeFile
Open "file.txt" For Random As FF Len = 242
Put FF, RecordNumber, CurrentRecord
Close #FF
End Sub

How do I do this sort of thing in Csharp? I can't seem to find a way to
read/write fixed sized records.

Thanks

Alan

[Nicholas Paldino [.NET/C# MVP]]

Re: Random Access Files

Alan,

There really isn't a simple way to do this.

The best way to do this would be to declare the LogEntry class with the
properties that you specify. Then, I would have a method which would
perform the serialization of the items into a byte array which is 242 bytes
long.

Then, you would have a method which would open the file, move the file
pointer to the appropriate location, write the record, and then close it.

Hope this helps.

--
- Nicholas Paldino [.NET/C# MVP]
- mvp@spam.guard. caspershouse.co m

"Alan Roberts" <alan@statistix l.co.uk> wrote in message
news:OhHTTeXBGH A.1088@tk2msftn gp13.phx.gbl...[color=blue]
> In VB6 I could use random access and fixed record lengths to read specific
> records from a test file. Eg the following code would save a LogEntry to
> a file at the location specified by RecordNumber.
>
> Private Type LogEntry
> Date As String * 20
> Number As String * 20
> Source As String * 100
> Description As String * 100
> CRLF As String * 2
> End Type
> Public Sub RecordError(Num As Long, Source As String, Desc As String)
> Dim FF As Integer
> Dim CurrentRecord As LogEntry
> 'set the record values
> With CurrentRecord
> .Date = Trim(Format$(No w, "DD/MM/YYYY HH:MM:SS"))
> .Number = Num
> .Source = Trim(Source)
> .Description = Trim(Desc)
> .CRLF = vbCrLf
> End With
> 'save the record
> FF = FreeFile
> Open "file.txt" For Random As FF Len = 242
> Put FF, RecordNumber, CurrentRecord
> Close #FF
> End Sub
>
> How do I do this sort of thing in Csharp? I can't seem to find a way to
> read/write fixed sized records.
>
> Thanks
>
> Alan
>[/color]