Stack Memory

Creating a String puts fixed-sized data on the stack and dynamically sized data on the heap:

fn main() {
    let s1 = String::from("Hello");
}
StackHeaps1ptrHellolen5capacity5

  • Mention that a String is backed by a Vec, so it has a capacity and length and can grow if mutable via reallocation on the heap.

  • If students ask about it, you can mention that the underlying memory is heap allocated using the System Allocator and custom allocators can be implemented using the Allocator API