import (

	"crypto/rand"

	"fmt"

	"math"

	"math/big"

)

func main() {

	// 生成 1000 个 [-10, 10) 范围的安全随机数。

	for i := 0; i < 1000; i++ {

		ret := RangeRand(-10, 10)

		fmt.Println(ret)

	}

}

// 生成区间[-m, n]的安全随机数

func RangeRand(min, max int64) int64 {

	if min > max {

		panic("the min is greater than max!")

	}

	if min < 0 {

		f64Min := math.Abs(float64(min))

		i64Min := int64(f64Min)

		result, _ := rand.Int(rand.Reader, big.NewInt(max + 1 + i64Min))

		return result.Int64() - i64Min

	} else {

		result, _ := rand.Int(rand.Reader, big.NewInt(max-min+1))

		return min + result.Int64()

	}