I'm new to rust, and I'm trying to get my hands dirty, so I'm trying to implement quicksort, as part of one of the exercises of "The Book" ( probably the writer didn't intend to suggest to go this deep though, but isn't it the best way to learn? :) )
this is what I have so far:
fn quicksort(v: &mut Vec<i32>) {
// helper funtions for sorting the partitional vectors
fn partition(v: &mut Vec<i32>, lo: i32, hi: i32) {
// pivot
let mut p: i32;
let mut i = lo;
for j in i..hi {
}
}
fn quicksort(v: &mut Vec<i32>, lo: i32, hi: i32) {
// pivot
let mut p: i32;
if lo < hi {
p = partition(v, lo, hi);
}
}
quicksort(v, 0, (v.len() -1).try_into().unwrap())
}
when I try to compile I get this:
[foo12@archT520 vectors]$ cargo run
Compiling vectors v0.1.0 (/home/foo12/programs/rust/book/vectors)
error[E0308]: mismatched types
--> src/main.rs:36:10
|
36 | p = partition(v, lo, hi);
| ^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `()`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.
error: could not compile `vectors`
To learn more, run the command again with --verbose.
I don't see what I'm screwing up.
Also, I'd be glad to get a complete implementation of quicksort which doesn't use other libraries. Probably I could learn from it.
EDIT: I'm also not sure if this way of "shadowing" with the function name "quicksort" is going to work. I changed it before, so it's not the cause of the error, but I'd like to see if it's going to work this way, that's why I left it like this.
Your fn partition(v: &mut Vec<i32>, lo: i32, hi: i32) is not returning anything (denoted in Rust as having the return type ()), so you cannot assign the result to a variable of type i32.