func StrToInt(v string)(r int, err error){
	r, err=strconv.Atoi(v)
	if nil!= err{
		err = ErrInvalidNumber
		return
	}
	return
}
// if cannot change, return 0
if cannot change, return 0
// if cannot change return 0
func StrToInt(v string)(r int, err error){
	r, err=strconv.Atoi(v)
	if nil!= err{
		err = ErrInvalidNumber
		return
	}
	return
}
func StrToInt ( v string ) ( r int , err error ) { r , err = strconv . Atoi ( v ) if nil != err { err = ErrInvalidNumber return } return }
if cannot change, return 0
if cannot change return 0