hehe, thanks, so if i want understand deeply, need to look up gc code?
在 2019年4月3日星期三 UTC+8下午10:34:57，Ian Lance Taylor写道：
>
> On Wed, Apr 3, 2019 at 6:32 AM <mount...@gmail.com <javascript:>> wrote:
> >
> > thanks! v must be a value copy，Is this determined by the compiler?
>
> It's determined by the language definition.
>
> Ian
>
>
> > 在 2019年4月3日星期三 UTC+8下午7:57:26，Marvin Renich写道：
> >>
> >> * mount...@gmail.com <mount...@gmail.com> [190403 05:10]:
> >> > package main
> >> >
> >> > func main() {
> >> > b := []int{1}
> >> >
> >> > bb := make([]*int, 0, 1)
> >> > for k, v := range b {
> >>
> >> The above range clause will assign to k the index of the current
> >> element, and it will assign to v a copy (as if v = b[k]) of the element
> >> at that index.
> >>
> >> Go does not have references of the kind that C++ or Java has, so v
> >> cannot be a reference, in that sense, to b[k]; it must be a value copy.
> >>
> >> If what you really want is to be able to refer to the location of the
> >> element in the slice (really its backing array), omit the v in the
> range
> >> clause and just use &b[k]:
> >>
> >> for k := range b {
> >> _ = &b[k] // do what you want
> >> }
> >>
> >> > _ = &v //8 line
> >> > _ = &b[k] //9 line
> >> > // bb = append(bb, &v)
> >> > bb = append(bb, &b[k])
> >> > }
> >> >
> >> > // for _, v := range bb {
> >> > // fmt.Println(*v)
> >> > // }
> >> > }
> >>
> >> ...Marvin
> >>
> > --
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