如何在Golang中为单值上下文错误修复多值？

package main
import "fmt"

func main() {
    fmt.Println("Enter a number: ")
    var addendOne int = fmt.Scan()
    fmt.Println("Enter another number: ")
    var addendTwo int = fmt.Scan()
    sum := addendOne + addendTwo
    fmt.Println(addendOne, " + ", addendTwo, " = ", sum)
}

This raises an error:

multiple values in single-value context.

Why does it happen and how do we fix it?

fmt.Scan() returns two values and your code expects just one when you call it.

The Scan signature func Scan(a ...interface{}) (n int, err error) returns first the number of scanned items and eventually an error. A nil value in the error position indicates that there was no error.

Change your code like this:

addendOne, err := fmt.Scan()
if err != nil {
    //Check your error here
}

fmt.Println("Enter another number: ")
addendTwo, err := fmt.Scan()
if err != nil {
    //Check your error here
}

If you really want to ignore the errors you can used the blank identifier _:

addendOne, _ := fmt.Scan()

fmt.Scan return two values, and you're only catching one into addedOne. you should catch the error as well like this:

addendTwo, err := fmt.Scan() 
if err != nil {
  // handle error here
}

if you want to ignore the error value (not recommended!), do it like this:

addendTwo, _ := fmt.Scan() 

Because Scan returns int and error so you should use the := syntax that is shorthand for declaring and initializing.

addendOne, err := fmt.Scan()
addendTwo, err := fmt.Scan()

From golang fmt documentation:

func Scan(a ...interface{}) (n int, err error)