How to Propagate Errors from main() in Rust

Use the ? operator to immediately return the error from main() if a function call fails, or wrap the error handling logic in a separate function and return a Result.

use std::fs::File;
use std::io::Error;

fn main() -> Result<(), Error> {
    let file = File::open("hello.txt")?;
    Ok(())
}

Alternatively, use panic! to stop execution on unrecoverable errors:

fn main() {
    let file = File::open("hello.txt").expect("Failed to open file");
}

In Rust, main() can return a Result type to pass errors up to the operating system instead of crashing the program. Think of it like a worker handing a rejected package back to the manager rather than throwing it on the floor. This allows the system to handle the failure gracefully.