切片

切片能讓您查看更大的集合：

fn main() {
    let mut a: [i32; 6] = [10, 20, 30, 40, 50, 60];
    println!("a: {a:?}");

    let s: &[i32] = &a[2..4];

    println!("s: {s:?}");
}

This slide should take about 10 minutes.

我們會建立一個切片，方法是先借用 a，然後在括號中指定起始和結束索引。
如果切片從索引 0 開始，Rust 的範圍語法可允許我們捨棄起始索引，也就是說，&a[0..a.len()] 和 &a[..a.len()] 意思相同。
同理，最後一個索引也是如此，因此 &a[2..a.len()] 和 &a[2..] 意思相同。
因此，為了輕鬆建立完整陣列的切片，我們可以使用 &a[..]。
s 是對 i32s 切片的參照。請注意，s (&[i32]) 的型別不再提及陣列長度，這有利於我們對不同大小的切片執行運算。
Slices always borrow from another object. In this example, a has to remain 'alive' (in scope) for at least as long as our slice.
The question about modifying a[3] can spark an interesting discussion, but the answer is that for memory safety reasons you cannot do it through a at this point in the execution, but you can read the data from both a and s safely. It works before you created the slice, and again after the println, when the slice is no longer used.

Comprehensive Rust 🦀