Golang String Formatting

I have the below code,

package main
import "fmt"

func main() {
    var s1 []int
    //s2 := []int{}

    fmt.Printf("%d, %d, %T, %t, %#[3]v\n", len(s1), cap(s1), s1, s1 == nil)
}

and the output is,

0, 0, []int, true, []int(nil)

Im really confused with the use of "%[3]v",.. since Im passing only 4 arguments…

The output I was expecting is

0, 0, []int, true

But "[]int(nil)" in the output is confusing me a bit.

>Solution :

If u want to get 0, 0, []int, true, pls use this:

fmt.Printf("%d, %d, %T, %t\n", len(s1), cap(s1), s1, s1 == nil)

Your code:

fmt.Printf("%d, %d, %T, %t, %#[3]v\n", len(s1), cap(s1), s1, s1 == nil)

%#[3]v refers to the third argument, which is s1. []int(nil) is the default representation of an empty slice of integers.