understand underscore

main.go

package main
import “fmt”
func main() {
    s := []int{10, 20, 30, 40, 50, 60, 70, 80, 90}
    fmt.Println(“--------\nindexWithValue\n--------“)
    indexWithValue(s)
    fmt.Println(“--------\nindexOnly\n--------“)
    indexOnly(s)
    fmt.Println(“--------\nvalueOnly\n--------“)
    valueOnly(s)
    fmt.Println(“--------\nnoValue\n--------“)
    noValue(s)
}

func indexWithValue(slice []int) {
    for index, value := range slice {
     fmt.Println(index, value)
    }
}

func indexOnly(slice []int) {
    for index := range slice {
    fmt.Println(index)
    }
}

func valueOnly(slice []int) {
    for _, value := range slice {
    fmt.Println(value)
    }
}

func noValue(slice []int) {
    for range slice {
    fmt.Println(“foo”)
    }
}