Is it possible to modify the array structure after its creation?

In Go, arrays have a fixed length that is set at creation and cannot be changed. If you need to change the size, you use slices, which are dynamic wrappers over arrays.

Example:

var arr [3]int = [3]int{1, 2, 3} // array of length 3

// You cannot do arr = [4]int{...} — that is a different array

// For dynamic size, use slices:
slice := []int{1, 2, 3}
slice = append(slice, 4) // now length is 4

Thus, the array structure is fixed, and slices are used for mutable collections.