How can I replace part of a slice with another in go

Question

I would like to see if there is a simple way to replace a portion of a slice with all the values of another slice. For instance:

x := []int{1,2,0,0}
y := []int{3,4}

// goal is x == {1,2,3,4}

x[2:] = y    // compile error
x[2:] = y[:] // compile error

I know that I can always iterate through through y, but Go has a bunch of cool features and I'm pretty new to Go. So perhaps I'm going about this the wrong way.

Answer 1

You can use the builtin copy:

The copy built-in function copies elements from a source slice into a destination slice.

package main

import "fmt"

func main() {
    x := []int{1, 2, 0, 0}
    y := []int{3, 4}

    copy(x[2:], y)

    fmt.Println(x) // [1 2 3 4]
}

• https://play.golang.org/p/TL6Bv4OGeqE

Stealing from the above comment, you can learn more on slices here:

• https://golang.org/ref/spec#Appending_and_copying_slices
• https://golang.org/doc/effective_go.html#slices
• https://github.com/golang/go/wiki/SliceTricks

I also found this blog post informative: https://divan.dev/posts/avoid_gotchas/#arrays-and-slices