random - 去 rand.Intn 相同的数字/值

Question

谁能告诉我为什么这里是 Go 示例:

https://tour.golang.org/basics/1

总是为 rand.Intn(10) 返回相同的值？

Answer 1

2 个原因:

1. 你必须初始化全局Source由 rand.Intn() 使用和 rand 包的其他函数使用 rand.Seed() .例如:

   rand.Seed(time.Now().UnixNano())
   

   查看Difficulty with Go Rand package 的可能重复项.
   引用 rand 的包文档:

   Top-level functions, such as Float64 and Int, use a default shared Source that produces a deterministic sequence of values each time a program is run. Use the Seed function to initialize the default Source if different behavior is required for each run.

2. Tour在 Go Playground 上运行示例缓存其输出。
   详情见 Why does count++ (instead of count = count + 1) change the way the map is returned in Golang .