Mastering Rust - Second Edition

A sample program – buggie

We'll need a program to debug to experience gdb. Let's create a new project by running cargo new buggie. Our program will have a single function, fibonacci, which takes a position of n as usize, and gives us the nth Fibonacci number. This function assumes that the initial values of the Fibonacci numbers are 0 and 1. The following code is the program in its entirety:

1 // buggie/src/main.rs2 3 use std::env;4 5 pub fn fibonacci(n: u32) -> u32 {6     let mut a = 0;7     let mut b = 1;8     let mut c = 0;9     for _ in 2..n {10        let c = a + b;11        a = b;12        b = c;13    }14    c15 }16 17 fn main() {18     let arg = env::args().skip(1).next().unwrap();19     let pos = str::parse::<u32>(&arg).unwrap();20     let nth_fib = fibonacci(pos);21 println!("Fibonacci ...