Mastering Go - Second Edition

The copy() function

You can create a slice from the elements of an existing array and you can copy an existing slice to another one using the copy() function. However, as the use of copy() can be very tricky, this subsection will try to clarify its usage with the help of the Go code of copySlice.go, which will be presented in four parts.

You should be very careful when using the copy() function on slices because the built-in copy(dst, src) copies the minimum number of len(dst) and len(src) elements.

The first part of the program comes with the next Go code:

package main import ( "fmt" ) func main() { a6 := []int{-10, 1, 2, 3, 4, 5} a4 := []int{-1, -2, -3, -4} fmt.Println("a6:", a6) fmt.Println("a4:", a4) copy(a6, a4) fmt.Println("a6:", a6) ...