The correct way to create a new slice using the Golang loop

I recently ran into a problem with developing Web applications using Golang.

I wrote an interface to filter a list of people’s credentials.

http://127.0.0.1:11088/api/v1/person-auths?status=0,2
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The status field is a filter condition. For example, 0 and 2 are used to query authentication records of all personnel whose status is 0 and 2.

In the GIN framework, you can use ctx.query to retrieve the string corresponding to status.

statusStr := ctx.Query("status")/ / 1, 2
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The query parameter structure type for the business logic layer defines this:

type PersonAuthQueryParam struct {
	Status    []int
	// ...
}
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So I need to convert the string 1,2 to a slice of int [1, 2].

By JavaScript convention, this is pretty simple.

statusStr := "1, 2,"
statusStrs := strings.Split(statusStr, ",")
var statusInts []int
for i, v := range statusStrs {
    vInt, err := strconv.Atoi(v)
    iferr ! =nil {
        return err
    }
    statusInts[i] = vInt
}
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The logic is to split the string into a string slice and then create an empty int slice. Iterating over the string slice, converting the type of each element to int and assigning the value above the corresponding index of the int slice.

But at actual runtime, you get a Runtime error.

panic: runtime error: index out of range [0] with length 0
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This is a standard array out of bounds problem.

Because the int slice is empty, its length and capacity are both 0.

fmt.Printf("%v\n".len(statusInts))/ / 0
fmt.Printf("%v\n".cap(statusInts))/ / 0
fmt.Printf("%v\n", statusInts == nil)// true
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There are two ways to solve this.

The first is to add elements in a different way.

Use the append function to add elements, and it automatically expands.

statusInts = append(statusInts, vInt)
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The second option is to initialize the slice in a different way by giving the slice a length.

statusInts := make([]int.len(statusStrs))
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