How does the copy function work in the Go language and in what cases is its use justified?

In Go, the copy function is used to copy elements from one slice to another. It has the signature:

func copy(dst, src []Type) int

copy copies the minimum of the lengths of dst and src elements and returns the number of elements copied.

It is justified to use when you need to create a copy of a slice or copy part of the data into another slice to avoid changing the original data when modifying the new slice.

Example:

src := []int{1, 2, 3, 4}
dst := make([]int, len(src))
count := copy(dst, src)
fmt.Println(dst) // [1 2 3 4]
fmt.Println(count) // 4

This is useful for creating independent copies of slices.