dictionary - 插入 map 时，Go(深)复制键吗？

Question

我有一个带有复杂键的 map - 例如，二维数组:

m := make(map[[2][3]int]int)

当我在映射中插入一个新键时，Go 是否会对该键进行深度复制？

a := [2][3]int{{1, 2, 3}, {4, 5, 6}}
m[a] = 1

换句话说，如果我在将数组 a 用作映射键后更改它，映射是否仍然包含 a 的旧值？

Answer 1

简答，已复制。

根据规范，数组是值类型。

Go's arrays are values. An array variable denotes the entire array; it is not a pointer to the first array element (as would be the case in C). This means that when you assign or pass around an array value you will make a copy of its contents. (To avoid the copy you could pass a pointer to the array, but then that's a pointer to an array, not an array.) https://blog.golang.org/go-slices-usage-and-internals

自己看看:

https://play.golang.org/p/fEUYWwN-pm

package main

import (
    "fmt"
)

func main() {
    m := make(map[[2][3]int]int)
    a := [2][3]int{{1, 2, 3}, {4, 5, 6}}

    fmt.Printf("Pointer to a: %p\n", &a)

    m[a] = 1
    for k, _ := range m {
        fmt.Printf("Pointer to k: %p\n", &k)
    }
}

指针不匹配。

编辑:真正的原因是当插入 map 时，键值被复制。或者，你可以继续只记住上面的规则:数组是值类型，它们的重用表示一个副本。要么在这里工作。 :)