Memory mapped file question

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2 total messages Started by Totte Karlsson Sat, 19 Apr 2008 01:40

#388

Author: Totte Karlsson
Date: Sat, 19 Apr 2008 01:40

15 lines
1396 bytes

Hi,
I'm planning on using memory mapped files to write data to a file. The files can 
be of any size between 0 bytes to to 2GB (not larger).

My "problem" is, when I open the memory mapped file, I don't know how big it 
will be, i.e. h ow many bytes that I will write to it. And it seems that memory 
mapped files can't grow easily. So I thought I would open each file as 2 GB 
large initially and then, when I have written my bytes, say 1.38 GB, I would 
truncate the rest of the file.

Is that possible/feasible? Any simple answer on how to remove x bytes in a file 
from the end of file?

regards
-totte

Re: Memory mapped file question

#389

Author: Bob Gonder
Date: Sat, 19 Apr 2008 18:54

10 lines
1187 bytes

Totte Karlsson wrote:

>Is that possible/feasible? Any simple answer on how to remove x bytes in a file 
>from the end of file?

First set position to cutoff point.
	ret = SetFilePointer( h, offset, NULL, FILE_BEGIN );

Then Truncate it.
	ret = SetEndOfFile(h);

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