MemoryMappedFile syntax issue

Question

1.33/5 (2 votes)

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Trying to use MemoryMappedFile to read a file a piece at a time, analyze and change, then write out a new file. The VS syntax checker keeps rejecting the "Read" and "Write" specification. Here's what I have:

C#

MemoryMappedFile mInputFile = MemoryMappedFile.CreateOrOpen(fileToRead, fInputSize,Read);
MemoryMappedFile mOutputFile = MemoryMappedFile.CreateOrOpen(fileToWrite, fInputSize,Write);
int sliceSize = 65536;
using (var mInputAccessor = mInputFile.CreateViewAccessor(0, fInputSize))
{
   byte[] sliceArray = new byte[sliceSize];
   using (var mOutputAccessor = mOutputFile.CreateViewAccessor(0, fInputSize))
   {
      for (long i=0;i< fInputSize;i+=sliceSize)
      {
         mInputAccessor.ReadArray(i, sliceArray, 0, sliceSize);
            
             <<<do some="" processing="" here="">>>

         mOutputAccessor.WriteArray(i, sliceArray, 0, sliceSize);
       }
    }
}</do>

Posted 8-Oct-15 8:46am

mlowry

Updated 8-Oct-15 8:51am

Suvendu Shekhar Giri

v3

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Sergey Alexandrovich Kryukov 8-Oct-15 15:15pm

In what line? (Of course it will reject </do> :-)
—SA

2 solutions

Solution 2

Thanks for the solution and the editorial. I have been working with "advanced I/O programming" since 1968 on at least 10 different platforms. Aside from re-inventing solutions to problems solved 20 years ago I'm not sure Microsoft has advanced the state of the art much.

Adding layers and layers of obtuse syntax and calls with 20 overrides does little to advance the state of the art except to create an army of "experts" who live for esoteric coding techniques that require lengthy study to understand very simple things.

Posted 29-Oct-15 7:29am

mlowry

Comments

Richard Deeming 29-Oct-15 14:00pm

Don't post comments as new solutions. Use the "Have a Question or Comment?" button under the solution you want to respond to.

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Sergey Alexandrovich Kryukov · Accepted Answer · 2015-10-08T09:23:00

The first bug I can see is: last parameter of your MemoryMappedFile.CreateOrOpen call is supposed to be System.IO.MemoryMappedFiles.MemoryMappedFileAccess.Read and System.IO.MemoryMappedFiles.MemoryMappedFileAccess.Write:
https://msdn.microsoft.com/en-us/library/dd267576%28v=vs.110%29.aspx[^],
https://msdn.microsoft.com/en-us/library/system.io.memorymappedfiles.memorymappedfileaccess%28v=vs.110%29.aspx[^].

The namespace part of the type name, "System.IO.MemoryMappedFiles.MemoryMappedFileAccess" can be moved to "using".

Look, the problem is way too trivial; it's just about understanding C# very basic syntax and semantic and the ability to use the FCL documentation in a straightforward way. There is no such thing as "MemoryMappedFile syntax", it's about very basic language syntax and understanding of such basic things as type names and namespaces. I'm not sure you can advanced I/O programming without learning the language and platform properly; I personally would not even try before I learn the language.

—SA