Re: Memory-mapped file example sought

From:

Tim Roberts <timr@probo.com>

Newsgroups:

microsoft.public.vc.language

Date:

Thu, 31 Aug 2006 21:25:03 -0700

Message-ID:

<2fdff2tquq2mbmuh458ohd66i1hik9aso0@4ax.com>

dtheese@yahoo.com wrote:

I've seen a ton of documentation and examples on memory-mapped files,
and frankly I'm overwhelmed. I'm having a hard time distilling out of
all this information how to do the following most-basic task:

I want to map a file into my process address space and get two unsigned
char *, one to the very first byte of the file and one to the very last
byte of the file. I will then read and write as I have to between these
two addresses to accomplish what I want. Then I'll release the memory
mapped file and I'll be done.

Does anybody know of a succinct example out there that will clearly
show me how to map the file, get the two pointers I desire, and release
the mapping?

The easy way is to let ATL help you:

#include <stdio.h>
#include <atlfile.h>

int main(void)
{
    CAtlFile f;
    f.Create( "wm2.py", GENERIC_READ, FILE_SHARE_READ, OPEN_ALWAYS );

    CAtlFileMapping<unsigned char> map;
    map.MapFile( f );

    printf( "%d bytes\n", map.GetMappingSize() );
    unsigned char * pj = map;
    printf( "Start is %p, end is %p\n", pj, pj+map.GetMappingSize() );
    return 1;
}
--
- Tim Roberts, timr@probo.com
  Providenza & Boekelheide, Inc.