X-Git-Url: https://git.ralfj.de/rust-101.git/blobdiff_plain/229b86d07e94cd3ec175051a44b3f3cb45b40b65..a3a64118702b4f75691de78d42256c306f286014:/workspace/src/part00.rs?ds=sidebyside diff --git a/workspace/src/part00.rs b/workspace/src/part00.rs index 4f7b403..9144eae 100644 --- a/workspace/src/part00.rs +++ b/workspace/src/part00.rs @@ -1,5 +1,3 @@ -// ***Remember to enable/add this part in `main.rs`!*** - // Rust-101, Part 00: Algebraic datatypes // ====================================== @@ -17,18 +15,16 @@ enum NumberOrNothing { fn vec_min(vec: Vec) -> NumberOrNothing { let mut min = NumberOrNothing::Nothing; - // Now we want to *iterate* over the list. Rust has some nice syntax for - // iterators: + // Now we want to *iterate* over the list. Rust has some nice syntax for iterators: for el in vec { - // So `el` is al element of the list. We need to update `min` accordingly, but how do we get the current + // So `el` is an element of the list. We need to update `min` accordingly, but how do we get the current // number in there? This is what pattern matching can do: match min { // In this case (*arm*) of the `match`, `min` is currently nothing, so let's just make it the number `el`. NumberOrNothing::Nothing => { unimplemented!() }, - // In this arm, `min` is currently the number `n`, so let's compute the new minimum and store it. We will write - // the function `min_i32` just after we completed this one. + // In this arm, `min` is currently the number `n`, so let's compute the new minimum and store it. NumberOrNothing::Number(n) => { unimplemented!() } @@ -52,28 +48,20 @@ fn min_i32(a: i32, b: i32) -> i32 { // Indeed, we can: The following line tells Rust to take // the constructors of `NumberOrNothing` into the local namespace. -// Try moving that above the function, and removing all the occurrences `NumberOrNothing::`. +// Try moving that above the function, and removing all the occurrences of `NumberOrNothing::`. use self::NumberOrNothing::{Number,Nothing}; // To call this function, we now just need a list. Of course, ultimately we want to ask the user for // a list of numbers, but for now, let's just hard-code something. -// `vec!` is a *macro* (as you can tell from the `!`) that constructs a constant `Vec<_>` with the given -// elements. fn read_vec() -> Vec { - vec![18,5,7,1,9,27] + unimplemented!() } -// Finally, let's call our functions and run the code! -// But, wait, we would like to actually see something, so we need to print the result. -// Of course Rust can print numbers, but after calling `vec_min`, we have a `NumberOrNothing`. -// So let's write a small helper function that prints such values. +// Of course, we would also like to actually see the result of the computation, so we need to print the result. fn print_number_or_nothing(n: NumberOrNothing) { - match n { - Nothing => println!("The number is: "), - Number(n) => println!("The number is: {}", n), - }; + unimplemented!() } // Putting it all together: @@ -83,7 +71,6 @@ pub fn main() { print_number_or_nothing(min); } -// Now try `cargo run` on the console to run above code. +// Finally, try `cargo run` on the console to run it. -// [index](main.html) | previous | [next](part01.html)