Go rand 随机数

rand.New(rand.NewSource(time.Now().UnixNano()))
 

func RandRegMobile() (mobile int64) {
	var randSource = rand.New(rand.NewSource(time.Now().UnixNano()))
	nano := time.Now().UnixNano()
	r := randSource.Int63() & nano
	prefix := 20 + (r/10)%10
	idx := r % 10
	if idx < 7 {
		mobile = prefix*1e9 + r%7e8
	} else if idx < 9 {
		mobile = prefix*1e9 + r%2e8 + 7e8
	} else {
		mobile = prefix*1e9 + r%1e8 + 9e8
	}

	if mobile < 2e10 || mobile >= 3e10 {
		mobile = 2e10
	}
	return
}

func RandRegMobile() (mobile int64) {
	nano := time.Now().UnixNano()
	r := rand.Uint64() + uint64(nano)
	nano1 := time.Now().UnixNano()
	r1 := (rand.Uint64() + uint64(nano1)) % 9
	idx := r % 10
	suffix := r % 1e8
	mobile = int64(2e10 + idx*1e9 + r1*1e8 + suffix)
	if mobile < 2e10 || mobile >= 3e10 {
		mobile = 2e10
	}
	return
}

参考文档