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?\n1: Add\n2: Subtract\n3: Divide\n4: 
    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