从命令行询问两个整数-GOlang [关闭]

Question

I am perfectly fine with asking one integer input from user, but with two, it fails with "no new variables on left side of :=(undefined)"

and i dont see any ideas how to fix it..

i tried to create two variable-s (int type). with one it works perfectly fine, but with adding other one, it wails..

var loop_count int
         fmt.Println("Insert start ID : ")

         _, err1 := fmt.Scanf("%d", &loop_count)

         if err1 != nil {
            fmt.Println(err)
         }

    arr := make([]uint8, loop_count) //How many times it loops

    var url_id int
         fmt.Println("Insert start ID : ") //From where it starts

         _, err := fmt.Scanf("%d", &url_id)

         if err != nil {
            fmt.Println(err)
         }

         fmt.Println("Starting download from : ", url_id)

So i want to ask two things from console:

1. Loop count (how many times should it loop)
2. From what ID it should start downloading.

Answer 1

You get this error because you have already declare "err", when you using ":=" operator you are trying to redeclare(create the variable with the same name) this variable. You should use "=" to change value. And code blow work fine, but you`d better add validation:

var loop_count int
fmt.Print("Insert loop_count ID: ")

_, err := fmt.Scanf("%d", &loop_count)

if err != nil {
    fmt.Println(err)
}

var url_id int
fmt.Print("
Insert url_id ID: ") //From where it starts

_, err = fmt.Scanf("%d", &url_id)

if err != nil {
    fmt.Println(err)
}

fmt.Println("
Starting download from: ", url_id)