Range

The range form of the for loop iterates over a slice or map.

When ranging over a slice, two values are returned for each iteration. The first is the index, and the second is a copy of the element at that index.

range.go

package main
import "fmt"
var pow = []int{1, 2, 4, 8, 16, 32, 64, 128}
func main() {
    for i, v := range pow {
        fmt.Printf("2**%d = %d\n", i, v)
    }
}