Golang：函数的多个返回值的范围

Question

When a function returns more than one variable in Golang, what's the scope of the variables? In the code attached, I can't figure out the scope of b.

package main

import (
    "fmt"
)

func addMulti(x, y int) (int, int) {
    return (x + y), (x * y)
}

func main() {
    //what is the scope of the b variable here?
    a, b := addMulti(1, 2)

    fmt.Printf("%d %d
", a, b)

    //what is the scope of the b variable here?
    c, b := addMulti(3, 4)

    fmt.Printf("%d %d
", c, b)

}   

Answer 1

We're not talking about the scope of the return value of a function but rather the scope of the variable you assign the return value to.

The scope of the variable b in your case is the function body, from the point at which you declare it.

At first you do it at this line:

a, b := addMulti(1, 2)

But then you use another Short Variable declaration at this line:

c, b := addMulti(3, 4)

which - since b is already declared - just assigns a new value to it. b will be in scope until the end of your main() function. Quoting from the Go Language Specification:

Unlike regular variable declarations, a short variable declaration may redeclare variables provided they were originally declared earlier in the same block with the same type, and at least one of the non-blank variables is new. As a consequence, redeclaration can only appear in a multi-variable short declaration. Redeclaration does not introduce a new variable; it just assigns a new value to the original.