arrays - 声明数组大小是否明确确定按值传递还是按引用传递？

Question

以数组副本不改变其父数组为例:

    a1 := [5]string{"English", "Japanese", "Spanish", "French", "Hindi"}
    a2 := a1 
    fmt.Println("a1 = ", a1) //[English Japanese Spanish French Hindi]
    fmt.Println("a2 = ", a2) //[English Japanese Spanish French Hindi]
    a2[1] = "German"
    fmt.Println("now a2 = ", a2) // [English German Spanish French Hindi]
    fmt.Println("and a1 = ", a1) // [English Japanese Spanish French Hindi]

毫不奇怪，a2 是副本，而不是引用。更改副本不应该更改另一个副本，它们保存在不同的地址。
现在看看如果我们不向 a1 声明大小会发生什么:

    a1 := []string{"English", "Japanese", "Spanish", "French", "Hindi"} // <--difference here
    a2 := a1
    fmt.Println("a1 = ", a1) //[English Japanese Spanish French Hindi]
    fmt.Println("a2 = ", a2) //[English Japanese Spanish French Hindi]
    a2[1] = "German"
    fmt.Println("now a2 = ", a2) // [English German Spanish French Hindi]
    fmt.Println("and a1 = ", a1) // [English German Spanish French Hindi]

当 a2 改变时两者都改变​​？!所以，如果你没有为数组声明一个大小，然后将它分配给某个东西，突然它是一个引用？为什么 a2 := a1 的行为会完全不同，具体取决于另一个变量的声明方式？我很困惑哈哈。

Answer 1

我强烈建议阅读 Go 博客文章 Arrays, slices and strings - 然后再读一遍 - 它包含许多其他微妙的副作用。
它将显示幕后发生的事情以及 slice 类型的表示方式:

sliceHeader{
    Length:        0,
    Capacity:      0,
    ZerothElement: nil, // points to a fixed size array
}

因此变异操作如何影响多个 slice 值。
最后的报价:

Arrays have their place—they are a good representation of a transformation matrix for instance—but their most common purpose in Go is to hold storage for a slice.