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The definition of file number in the Open file syntax states that a FileNumber of 256 through 511 is to be used for files accessible from other applications.
Does anybody know what this really means? What is the difference between opening a random file ... As 1 vs ... As 256?
Thanks!
Where did you get that from?
FreeFile does not take a parameter. It returns the first available file number or an error if more than 255 file handles are currently in use.
http://msdn.microsoft.com/en-us/libr...(v=vs.90).aspx
I would expect open for input as #257 to crash with an error
Pretty sure 8-bit file handles were still in use. 0-255
I remember back in the days when it was not uncommon to only be able to have 3 or 4 open files at a time. Can't remember the exact syntax but there was a line in the cfg file to set max files and was almost always set to a number < 10
Ah... the olden days. Config.Sys, files=20, buffers=40... :)
I knew it had something to do with sys and cfg but I could not remember the name. Thankfully it has been a long time since I needed to edit one of these files. Now I have almost forgotten everything about it.
Really? Are younger programmers that forgetful? ;)
I must admit that I can remember the commands of my old CP/M system better than the .NET stuf I looked at last week.
I put that to WoF.System.Memory.Learning.Programming.NETstuff.Important.Recall again. :)
Its sad just how much my memory has went downhill in recent years. Used to be someone could talk with me for 10 minutes about a project and I would still remember the details 2 years later and now 10 minutes after the conversation I may not even remember having the conversation :(
I think I need to purcahse a new stick or 2 ;)
While I do still remember the old open file limitations this does not have anything to do with that (besides the file numbers were limited to 1 to 255 back then).
This is in VB6. The help screen for the "Open" statement lists the filenumber parameter and then the link on filenumber shows: "Use file numbers in the range 1-255, inclusive, for files not accessible to other applications. Use file numbers in the range 256-511 for files accessible from other applications."
And the FreeFile function accept an optional parameter: 0 = returns 1 - 255, 1 = returns 256-511. (the optional parameter defaults to 0 so it returns 1-255 as it always did).
Somebody at Microsoft obviously did this for a reason but I cannot find any additional information on it and in testing files opened with high vs. low file number and I cannot see the difference.
After some searching I found the info in the Op but nothing to expand on it so I have no idea what a filenumber above 255 would do in VB6. It appears these filenumbers are not supported in later versions of VB and I was not aware they could be used in VB6 until now.
The only thing that makes sense from the little info that is provided would be if you are opening a file to allow shared access but I was under the impression that the shared option was the method which should be used for this so again I do not know.
My take would be to stick with normal filenumbers 1-255
I must admit, I never heared about that optional parameter on FreeFile at all.
How do you share a file with another application anyway? One is reading it, the other is writing to it?
Could you post that link... I cant seem to find anything official..Quote:
Originally Posted by DataMiser
only this obscure post where he says that Freefile(1) allows you to access the next 255 file numbers...
It is actually in the msdn help that came with VB6 under the Open Statement.
Here is a link related to VBA which says pretty much the same thing.
http://msdn.microsoft.com/en-us/libr...(v=vs.60).aspx
This says File# (Channel #) can be 1-255 http://www.informit.com/library/cont...urs&seqNum=159