What is the difference between an array data structure and a slice in terms of usage and implementation features?

In Go, arrays and slices are different data structures with different properties:

• Array — a fixed-size sequence of elements of the same type. The size of the array is set at declaration and cannot be changed. Arrays are passed by value, meaning they are copied when assigned or passed to a function.

• Slice — a dynamic structure that references a part of an array with specified length and capacity. Slices allow resizing, adding elements with append. When passing a slice to a function, the slice structure (pointer, length, capacity) is copied, but not the underlying data.

Example:

var arr [3]int = [3]int{1, 2, 3} // fixed-size array

slice := arr[0:2] // slice referencing part of the array

slice = append(slice, 4) // slice can expand, creating a new array if necessary

Thus, slices are more flexible and convenient for working with dynamic data sets, while arrays are used when a fixed size and predictable behavior are needed.