if语句中的变量范围

Question

I've just started learning Go today and have got stuck on variable scopes.

I've ultimately confused about how to get around the fact that I can't create a variable inside an if statement and the use it afterward.

This is my code. The problem is that new1 can't be created before the if statement because its size is dependent upon the result of the if statement, and by creating it inside the if statement I can't use it after the if statement ends.

if len(array1)>len(array2) {
    new1 := make([]string,0,len(array1))
    mc := Array2Map_string(array1)
    for _,tok :=range array2 {
        _, ok := mc[tok]
        if ok {
            new1[len(new1)]=tok
            }
        }
    } else {
    new1 := make([]string,0,len(array2))
    mc := Array2Map_string(array2)
    for _,tok :=range array1 {
        _, ok := mc[tok]
        if ok {
            new1[len(new1)]=tok
            }
        }
    }
new2 := make([]string,0,len(new1))
copy(new2, new1)

The only thing I can think of is to do something like

var pointlessvariable uint
if len(array1)>len(array2) {
pointlessvariable=len(array1)
} else {
pointlessvariable=len(array2)
}
var new1 = make([]string,0,pointlessvariable)
if len(array1)>len(array2) {
...

To be quite honest if that is truly the solution then I don't think I want to use Golang after all.

So what is the best way of solving this?

Answer 1

You can declare new1 before the if block and use make inside:

var new1 []string

if len(array1)>len(array2) {
    new1 = make([]string, 0, len(array1))
    // instructions ...
} else {
    new1 = make([]string, 0, len(array2))
    // other instructions ...
}

new2 := make([]string, 0, len(new1))
copy(new2, new1)