golang 整数前置补0

package main
import (
	"fmt"
)
func main() {
    a := 11
    fmt.Println(a)
    //前置补0
    fmt.Printf("%09d", a) //9位，不足前面凑0补齐
    fmt.Println("")
    fmt.Printf("%0*d", 9, a) //同上
}