8.2 The main Function

Every Rust program must have exactly one main function, which serves as the entry point of the program.

fn main() {
    // Program entry point
}
  • Parameters: By default, the main function does not take parameters. However, you can use std::env::args to access command-line arguments.
  • Return Type: The main function typically returns the unit type (). You can also have it return a Result<(), E> for error handling.

8.2.1 Using Command-Line Arguments

To access command-line arguments, you can use the std::env module.

use std::env;
fn main() {
    let args: Vec<String> = env::args().collect();
    println!("Arguments: {:?}", args);
}

8.2.2 Returning a Result from main

fn main() -> Result<(), std::io::Error> {
    // Your code here
    Ok(())
}
  • Returning a Result allows the use of the ? operator for error handling in the main function.