I want to know do we have to call rand.Seed(n) manually in Go?
I have a code that looks like this:
import (
"fmt"
"math/rand"
)
func main() {
fmt.Println(rand.Intn(100))
fmt.Println(rand.Intn(100))
fmt.Println(rand.Intn(100))
}
Everytime I run this code, each line prints different numbers than the others.
So do I need to call rand.Seed(n) each time before calling rand.Intn(100)?
在GO 1.20之前，全局共享源在内部被设定为1，因此应用的每次运行都将产生相同的伪随机序列.
拨打rand.Seed() is not needed starting from Go 1.20.Release notes:
The 100 package now automatically seeds the global random number generator (used by top-level functions like 101 and 102) with a random value, and the top-level 103 function has been deprecated.需要可重现的随机数序列的程序应该更喜欢使用
rand.New(rand.NewSource(seed))来分配它们自己的随机源.需要更早一致的全局种子设定行为的程序可以在其环境中设置
GODEBUG=randautoseed=0.顶层
Read函数已弃用.在几乎所有的情况下，crypto/rand.Read更合适.
rand.Seed()在其文件中也有这样的规定:
已弃用:当依赖项更改了它从全局随机源消耗的量时，调用种子然后期望来自全局随机源的特定结果序列(使用Int等函数)的程序可能会中断.为了避免这种 destruct ，需要特定结果序列的程序应该使用NewRand(Newsource(Seed))来获得其他包无法访问的随机生成器.