用Go语言复制数组的功能

Question

Is there any built-in function in Go for copying one array to another? Will this work in case of two (or more) dimensional arrays?

Answer 1

Is there any built-in function in Go language for copying one array to another?

Yes: http://play.golang.org/p/_lYNw9SXN5

a := []string{
    "hello",
    "world",
}
b := []string{
    "goodbye",
    "world",
}

copy(a, b)

// a == []string{"goodbye", "world"}

---

Will this work in case of two (or more) dimensional arrays?

copy will do a shallow copy of the rows: http://play.golang.org/p/0gPk6P1VWh

a := make([][]string, 10)

b := make([][]string, 10)
for i := range b {
    b[i] = make([]string, 10)
    for j := range b[i] {
        b[i][j] = strconv.Itoa(i + j)
    }
}

copy(a, b)

// a and b look the same

b[1] = []string{"some", "new", "data"}

// b's second row is different; a still looks the same

b[0][0] = "apple"

// now a looks different

I don't think there's a built-in for doing deep-copys of multi-dimensional arrays: you can do it manually like: http://play.golang.org/p/nlVJq-ehzC

a := make([][]string, 10)

b := make([][]string, 10)
for i := range b {
    b[i] = make([]string, 10)
    for j := range b[i] {
        b[i][j] = strconv.Itoa(i + j)
    }
}

// manual deep copy
for i := range b {
    a[i] = make([]string, len(b[i]))
    copy(a[i], b[i])
}

b[0][0] = "apple"

// a still looks the same

edit: As pointed out in the comments, I assumed by "copy an array" you meant "do a deep copy of a slice", as arrays can be deep-copied with the = operator as per jnml's answer (because arrays are value types): http://play.golang.org/p/8EuFqXnqPB