Rust 2D slice example

main.rs

fn main() {
    /*
     * 1D array and slice
     */
    let array = [11u8, 12, 13, 14, 15]; // 1D array: 5 elems

    let slice: &[u8] = &array; // slice of 1D array
    for x in slice { // x: &u8
        print!("{} ", x);
    }
    println!();

    println!("---");

    /*
     * 2D array(mutable) and slice
     */
    let mut array = [[0u8; 3]; 5]; // 2D array: 5rows x 3cols

    // set 2D array values to [[1, 2, 3], [4, 5, 6], ...]
    let mut cnt = 0u8;
    for row in &mut array { // row: &mut [u8; 3]
        for col in row { // col: &mut u8
            cnt += 1;
            *col = cnt;
        }
    }

    let mut vec: Vec<&[u8]> = Vec::new(); // vector containing &[u8] which is type of 1D slice
    // first, make vector of row slices
    for row in &array {
        vec.push(row);
    }

    let slice: &[&[u8]] = &vec; // slice of 2D array by slicing vector
    for row in slice { // row: &&[u8]
        for col in *row { // col: &u8
            print!("{} ", col);
        }
        println!();
    }
}

>cargo run
11 12 13 14 15
---
1 2 3
4 5 6
7 8 9
10 11 12
13 14 15

Create a 2D slice and pass it to a function

use std::fmt::Display;
fn print2dslice<T: Display>(two2darr: &[&[T]]) {
    for (row_idx, row) in two2darr.iter().enumerate() {
        println!("");
        for (col_idx, elt) in row.iter().enumerate() {
            print!("[{} {} {}] ", row_idx, col_idx, elt);
        }
    }
}

fn main() {
    // * Create a 2D slice.
    let twoarray: [[u64; 4]; 5] = [[0u64; 4]; 5];
    let mut vector_slice_rows = Vec::new();

    for row in &twoarray {
        vector_slice_rows.push(&row[..]);
    }
    let sliceofslice: &[&[u64]] = vector_slice_rows.as_slice();
    print2dslice(&sliceofslice);
}