How do I use memory-mapped files in C++?

Memory-mapped files are a powerful feature in C++ that allow applications to map files or devices into memory. This allows applications to access files as if they were part of the virtual memory, which can improve performance for large files by allowing for easier read/write operations.

Example of Memory-Mapped Files in C++

#include #include #include #include #include int main() { const char *filePath = "example.txt"; int fd = open(filePath, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR); if (fd == -1) { std::cerr << "Error opening file!" << std::endl; return 1; } // Writing data to file const char *data = "Hello, Memory-Mapped Files!"; write(fd, data, strlen(data)); // Memory-mapping the file size_t fileSize = strlen(data); char *mapped = (char *)mmap(nullptr, fileSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (mapped == MAP_FAILED) { std::cerr << "Mapping failed!" << std::endl; return 1; } // Reading from memory-mapped file std::cout << "Mapped Data: " << mapped << std::endl; // Clean up munmap(mapped, fileSize); close(fd); return 0; }

Memory-mapped files C++ file I/O performance virtual memory

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