How to Use Memory-Mapped I/O in Rust

Rust does not provide built-in memory-mapped I/O; you must use the memmap2 crate to map files into memory. Add memmap2 = "0.9" to your Cargo.toml and use MmapOptions to create a mapping.

use memmap2::MmapOptions;
use std::fs::File;

fn main() {
    let file = File::open("data.bin").unwrap();
    let mmap = unsafe { MmapOptions::new().map(&file).unwrap() };
    println!("First byte: {}", mmap[0]);
}

Memory-mapped I/O lets your program treat a file on your disk as if it were a block of RAM. This is useful for reading large files quickly without loading them all at once. Think of it like opening a book and reading specific pages directly instead of photocopying the whole book first.