为什么Scanf（）无法为我正常工作？

Question

I'm trying to move from Python to GO and with my minimal knowledge I tried to make a basic calculator. However i for some reason can't get Scanf to work properly. It only seems to accept the first scanf but the second one is completely ignored

package main

import (
    "fmt"
)

var x int
var y int
var result int
var input float64

func add(x int, y int) int {
sum := x + y
return sum
}

func sub(x int, y int) int {
    sum := x - y
    return sum
}

func div(x int, y int) int {
    sum := x / y
    return sum
}

func mul(x int, y int) int {
sum := x * y
return sum
}

func main() {

    fmt.Println("Which type?
1: Add
2: Subtract
3: Divide
4: 
    Multiply")
    fmt.Scanf("%d", &input)

    fmt.Println("Input numbers seperated by space")
    fmt.Scanf("%d", x, y)

    switch input {
    case 1:
        result = add(x, y)

    case 2:
        result = sub(x, y)

    case 3:
        result = div(x, y)

    case 4:
       result = mul(x, y)
    }

    fmt.Println(result)
}

Answer 1

The second call to Scanf, Scanf("%d", x, y) only provides one conversion specifier but was given two variables.

Moreover, this second call only passes the variables' values, not their addresses.

It seems the correct call would be Scanf("%d %d", &x, &y)

---

In the first call to Scanf you said: Scanf("%d", &input). The second argument's syntax, & variable, denotes a reference to the named variable.

input was declared global, but is only visible after its declaration. Since input is in scope within main but not within Scanf, in order for Scanf to change the value in another scope, the address must be given as an argument, rather than its value.

The recipient of the address (here Scanf) can then change the value of the variable in the frame in which it is still in scope; in this case, main.

See Go's documentation for a similar explanation: https://golang.org/ref/spec#Address_operators