How is a slice organized under the hood in Go?

In Go, a slice is a structure that contains three main fields:

• pointer to array — the address of the first element of the slice in the underlying array;
• length (len) — the number of elements accessible in the slice;
• capacity (cap) — the maximum number of elements that can be stored in the underlying array starting from the pointer.

Under the hood, a slice is not an array but a "window" into a part of an array. When adding elements using append, if the length exceeds the capacity, a new larger array is created, and data is copied there.

Example of a slice structure (simplified):

type sliceHeader struct {
    ptr *ElementType
    len int
    cap int
}

This allows efficient work with dynamic arrays without copying data on each addition, as long as the current capacity is not exceeded.