Dear, Ian. You are correct and I was wondering why the reassignment did not work in the case of *x *var*. *I found the answer in the Effective Go documentation, in the *Redeclaration and reassignment* section:
In a := declaration *a variable v may appear even if it has already been > declared*, *provided*: > > - *this declaration is in the same scope as the existing declaration > of v *(if v is already declared in an outer scope, the declaration > will create a new variable §), > > Thanks for your help. Best regards. Paulo. Em ter, 18 de jan de 2022 00:17, Ian Lance Taylor <i...@golang.org> escreveu: > On Mon, Jan 17, 2022 at 7:07 PM Paulo Júnior <pauloafpjun...@gmail.com> > wrote: > > > > I'm studying about if statement and comma ok construction and I'm not > sure why the piece of code (https://go.dev/play/p/ScFJsih6lwR) bellow > does not work. The compiler says that: x declared but not used. However, x > is used in the second if statement of the main function, as you can see. > > > > It is worthy to notice that x is just assigned (not declared) in the > first if of the main function, because I declared it as follows: var x int > > > > func MyFunc() (int, bool) { > > return 1, true > > } > > > > func main() { > > var x int > > if x, ok := MyFunc(); !ok { > > fmt.Println("Err") > > } > > fmt.Println(x) > > } > > When you write "if x, ok := ... { }" that declares a new variable "x" > (and a new variable "ok") that are only visible in the if statement. > The "x" declared in the if statement shadows the "x" declared in "var > x int". That is, there are two different variables named "x" here. > The one declared in the "if" statement is not used. > > It looks like you may want to write something like > > var x int > var ok bool > if x, ok = MyFunc(); !ok { > fmt.Println("Err") > } > fmt.Println(x) > > Note the use of "=" rather than ":=" in the if statement. > > Ian > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CACtisV4kP-OVB60gNr3Spyhm9iys5o_upFM-eX-XkRHMxn6-nA%40mail.gmail.com.
