Arrays

1. ```
   fn main() {
   ```
2. ```
       let mut a: [i8; 10] = [42; 10];
   ```
3. ```
       a[5] = 0;
   ```
4. ```
       println!("a: {a:?}");
   ```
5. ```
   }
   ```

This slide should take about 5 minutes.

• A value of the array type [T; N] holds N (a compile-time constant) elements of the same type T. Note that the length of the array is part of its type, which means that [u8; 3] and [u8; 4] are considered two different types. Slices, which have a size determined at runtime, are covered later.
• Try accessing an out-of-bounds array element. Array accesses are checked at runtime. Rust can usually optimize these checks away, and they can be avoided using unsafe Rust.
• We can use literals to assign values to arrays.
• The println! macro asks for the debug implementation with the ? format parameter: {} gives the default output, {:?} gives the debug output. Types such as integers and strings implement the default output, but arrays only implement the debug output. This means that we must use debug output here.
• Adding #, eg {a:#?}, invokes a “pretty printing” format, which can be easier to read.