golang 常量的iota使用

package main

import (
"fmt"
)

type ByteSize float64

const (
_ = iota
KB ByteSize = 1 << (10*iota)
MB
GB
TB
PB
EB
ZB
YB
)

func (b ByteSize) String() string{
switch {
case b >= YB:
return fmt.Sprintf("%.2fYB",b/YB)
case b >= ZB:
return fmt.Sprintf("%.2fZB",b/ZB)
case b >= EB:
return fmt.Sprintf("%.2fEB",b/EB)
case b >= PB:
return fmt.Sprintf("%.2fPB",b/PB)
case b >= TB:
return fmt.Sprintf("%.2fTB",b/TB)
case b >= GB:
return fmt.Sprintf("%.2fGB",b/GB)
case b >= MB:
return fmt.Sprintf("%.2fMB",b/MB)
case b >= KB:
return fmt.Sprintf("%.2fKB",b/KB)

}
return fmt.Sprintf("%.2fB",b)
}

func main() {
fmt.Println(ByteSize(1e10))
}