Rust

13.2    References to Unsized Types

In this section, we’ll consider the size of a reference to an array and an array slice. Consider the code shown in Listing 13.4.

fn main() {    println!(        "Size of a reference to sized type: {}",        size_of::<&[i32; 3]>()    );    println!(        "Size of a reference to unsized type: {}",        size_of::<&[i32]>()    );}  

Listing 13.4     Displaying the Size of a Reference to an Array and Reference to an Array Slice

In the previous section, you learned that an array is a sized type, while an array slice is unsized. We also discussed how a simple reference is one machine word in size, which is typically 8 bytes on most machines. If you execute this code, you may notice the following output:

Size of a reference to sized type: 8Size of ...