File mapping is a concept where a file map object can be created for a file on the disk. Thereafter, different processes can create a view of this file mapping object in their virtual address spaces. A process can create one or more views of the file mapping object in its virtual address space and work on it. Below is the working diagram for the file mapping object:

File mapping is a technique used in computer programming that allows a program to access a file stored in the operating system's file system as if it were part of the program's memory space. This technique is particularly useful when working with large files or when multiple processes need to access the same file simultaneously.

In C++, file mapping is implemented using the functions provided by the operating system's API, such as the CreateFileMapping and MapViewOfFile functions in Windows. The process of using file mapping in C++ typically involves the following steps:

1. Open the file to be mapped using the operating system's file I/O functions.
2. Create a file mapping object using the CreateFileMapping function, specifying the file handle and the desired access rights.
3. Map a view of the file into the program's address space using the MapViewOfFile function, specifying the file mapping object, the desired access rights, and the desired starting offset and length of the mapping.
4. Use the memory mapped view of the file as if it were a regular array in the program's memory space, reading and writing to it as needed.
5. Unmap the view of the file using the UnmapViewOfFile function when finished.

Using file mapping in C++ can improve the performance and reliability of applications that need to access large files or shared data. However, it requires careful management of memory and synchronization between processes to avoid data corruption or other issues.