Creating a Memory Maped Object

What is it good for?
Mostly used to share data among processes and to have a faster access to files.
In addition it has no need in allocating new virtual memory and thus saves precious resources.
The first step is creating a memory map of the file, and the second step is to create a view of the map in the virtual memory.

This link shows a benchmark results of using various methods of file access.

More information can be found here

A simple example:

#include <sys\stat.h>
#include <stdlib.h>
#include <stdio.h>
#include <vector>
using namespace std;
__int64 FileSize64( const char * szFileName ) 
{ 
  struct __stat64 fileStat; 
  int err = _stat64( szFileName, &fileStat ); 
  if (0 != err) return 0; 
  return fileStat.st_size; 
}
char * g_buffer;

int _tmain(int argc, _TCHAR* argv[])
{
 const char fileName[] = "alex.c";
 long fileSize = (long)FileSize64(fileName);
 g_buffer = new char[fileSize];
 
 HANDLE hFile  = CreateFileA(fileName, GENERIC_READ, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, 0);  
 HANDLE hFileMapping = CreateFileMapping(hFile, 0, PAGE_READONLY, 0, fileSize, 0);

 int iPos = 0;
 const unsigned int BlockSize = 128 * 1024;

 while(iPos < fileSize)
 {      
  int iLeft = fileSize - iPos;
  int iBytesToRead = iLeft > BlockSize ? BlockSize: iLeft;

  void *rawBuffer = MapViewOfFile(hFileMapping, FILE_MAP_READ, 0, iPos, iBytesToRead);
  memcpy(&g_buffer[iPos], rawBuffer, iBytesToRead);      
  UnmapViewOfFile(rawBuffer);

  iPos += iBytesToRead;
 }        
                
 CloseHandle(hFileMapping);
 CloseHandle(hFile);
 printf("%s", g_buffer);
 
 system("pause");
 return 0;
}