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How to do CreateFileMapping in a C++ DLL and access it in C#, VB and C++

, 10 Mar 2009
This is yet another example for memory mapped files. What is cool though is unlike other samples, I have a SetData(TCHAR* Key, TCHAR* value) / GetData(TCHAR* key) pattern here.
MMF_SetData_GetData.zip
tubelite
bin
Client_CSharp.exe
Client_CSharp.vshost.exe
Client_CSharp.vshost.exe.manifest
Client_VBNET.exe
Client_Win32Console.exe
Client_Win32Console.ilk
SHAREDMEM.dll
SHAREDMEM.exp
SHAREDMEM.ilk
SHAREDMEM.lib
CSharpConsumer
bin
Debug
WindowsFormsApplication1.exe
Properties
Settings.settings
SHAREDMEM
module.def
Release
mt.dep
sharedmem.dll.intermediate.manifest
sharedmem.pch
vc90.idb
sharedmem.vcproj.Pranav-PC.Pranav.user
UnmanagedConsumer
Release
mt.dep
Test1.exe.intermediate.manifest
vc90.idb
Test1.vcproj.Pranav-PC.Pranav.user
VBNETConsumer
bin
My Project
Application.myapp
Settings.settings
// dllmain.cpp : Defines the entry point for the DLL application.
#include "stdafx.h"

HANDLE m_hFileMMF = 0, m_pViewMMFFile = 0, hMutex = 0;

BOOL CreateMMF()
{
	//Creation and Mapping of Memory Mapped File
	m_hFileMMF = CreateFileMapping(INVALID_HANDLE_VALUE,NULL,PAGE_READWRITE,0,MAX_PATH*MAX_PATH, L"SOMENAME");              
    DWORD dwError = GetLastError();
    if ( ! m_hFileMMF )
    {
        MessageBox(0, L"Creation of file mapping failed",0 ,0);
    }
    else
    {
        m_pViewMMFFile = MapViewOfFile(m_hFileMMF,FILE_MAP_ALL_ACCESS,0,0,0);                         // map all file

        if(! m_pViewMMFFile )
        {
            MessageBox(0, L"MapViewOfFile function failed" ,0,0);
        }
    }
	
	return m_pViewMMFFile!=NULL;
}

void DestroyMMF()
{
	//CloseHandle(hMutex);
	//CloseHandle(m_hFileMMF);
}

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
					 )
{
	switch (ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
		CreateMMF();
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
	case DLL_PROCESS_DETACH:
		DestroyMMF();
		break;
	}
	return TRUE;
}

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About the Author

nkrscorpio
Software Developer
United States United States
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