// Question 4. What will be displayed on the screen package main import "fmt" func subis(is []int) []int { is = append(is, 5) return append(is, 6) } func main() { is := []int{1, 2, 3, 4} subis(is[2:3]) fmt.Println(is) }

This code does the following:

• In main, a slice is created: is = []int{1, 2, 3, 4}
• The function subis is called with the argument is[2:3], which is a slice containing one element: {3}
• Inside subis, 5 is first appended to the slice, then 6 is appended to the result, and a new slice is returned
• However, the returned value from subis in main is not used, so the original slice is not changed

Important: slices in Go are structures with a pointer to an array, a length, and a capacity. When append is called, if the capacity of the slice is insufficient, a new array is created, and changes do not reflect on the original array.

In this case, is[2:3] is a slice of length 1 and capacity 2 (elements at indices 2 and 3 of the original array). When append(is, 5) is called, the capacity allows adding the element without copying, so the underlying array is modified.

Thus, after calling subis(is[2:3]), the original array is changed, specifically the element at index 3 (which is 4). But since the original array has length 4, index 4 does not exist, so append will create a new array.

Let's verify step by step:

• is[2:3] — element at index 2 (value 3), length 1, capacity 2 (elements at indices 2 and 3)
• append(is, 5) adds 5 at position index 3 of the original array, replacing 4 with 5
• append(is, 6) creates a new slice with elements {3, 5, 6}

But since the returned value is not used, the original slice is only changed at position index 3 — where 4 becomes 5.

Final output:

[1 2 3 5]

That is, the output on the screen will be: [1 2 3 5].