Then turn vo into a Vertex variable, not a pointer
var vp Vertex = Vertex{}
...
if v.X == 3 {
vp = v
}
….
This time vp will be a copy of v,
Maybe you have to give some known values and exceptional case for your
domain, I mean, vp Vertex = { -1, -1} or any values your are
positive does not exists because maybe {0,0} is good data.
HTH
PS: You can break nested loops from an inside loop using break [label]
El martes, 10 de septiembre de 2019, 14:29:50 (UTC-5), Tong Sun escribió:
>
>
>
> On Tuesday, September 10, 2019 at 3:18:47 PM UTC-4, burak serdar wrote:
>>
>> On Tue, Sep 10, 2019 at 1:13 PM Tong Sun <sunto...@gmail.com> wrote:
>> >
>> > I'm experiencing a weird problem with my program and finally nail it
>> down to what exactly went wrong, so that I can write a minimum program to
>> duplicate it. See the following program:
>> >
>> > package main
>> >
>> >
>> > import (
>> > "fmt"
>> > )
>> >
>> >
>> > type Vertex struct {
>> > X int
>> > Y int
>> > }
>> >
>> >
>> > func main() {
>> > vs := []Vertex{
>> > Vertex{1, 2}, // has type Vertex
>> > Vertex{X: 3}, // Y:0 is implicit
>> > Vertex{}, // X:0 and Y:0
>> > }
>> >
>> >
>> > fmt.Printf("Vertex Slice %+v\n", vs)
>> > var vp *Vertex = nil
>> > for _, v := range vs {
>> > if v.X == 3 {
>> > vp = &v
>> > }
>> > }
>> > fmt.Printf("Found: %+v\n", vp)
>> > }
>> >
>> >
>> > https://play.golang.org/p/R645C5plojx
>> >
>> > I was expecting that the found Vertex is "v.X == 3", however the result
>> is not.
>>
>> Because you're keeping a pointer to the loop variable. v continues
>> changing after you store the address of it, so you get the latest
>> value of v. Instead, save a copy of v, or break the loop as soon as
>> what you're looking for is found:
>>
>
> I can't break the loop immediately as my not-minimized real program use a
> double loop to find the *closest *item. That's the reason I using the
> pointer to track my finding...
>
> if v.x==3 {
>> t:=v
>> vp=&t
>> }
>>
>
> OK. will do that. thx
>
> >
>> > - what exactly is causing the problem?
>> > - how to fix it so that I got what I was looking for?
>> >
>> > Again, the snip is at
>> > https://play.golang.org/p/R645C5plojx
>> >
>> > Thanks
>> >
>> > --
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>> Groups "golang-nuts" group.
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>>
>>
>>
>
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