This commit is contained in:
Mark McGranaghan 2012-09-21 08:38:28 -07:00
parent 8612ba6589
commit c1addcaab4

View File

@ -1,26 +1,37 @@
// The `math/rand` package provides psuedo-random numbers.
package main
package main // The `math/rand` package provides psuedo-random
// numbers.
import (
"math/rand"
"fmt"
)
func main() {
fmt.Println(rand.Intn(100)) // For example, `rand.Intn` returns a random `int` n,
fmt.Println(rand.Intn(100)) // `0 <= n < 100`.
fmt.Print(rand.Intn(100), ",") // For example, `rand.Intn` returns a random `int` n,
fmt.Print(rand.Intn(100)) // `0 <= n < 100`.
fmt.Println()
fmt.Println(rand.Float64()) // `rand.Float64` returns a `float64` `f`, `0.0 <= f < 1.0`.
r1 := rand.New(rand.NewSource(int64(1337))) // To make the psuedo-random generator deterministic, give it a
// well-known seed.
fmt.Println(rand.Float64()) // `rand.Float64` returns a `float64` `f`,
// `0.0 <= f < 1.0`.
s1 := rand.NewSource(42) // To make the psuedo-random generator deterministic,
r1 := rand.New(s1) // give it a well-known seed.
fmt.Println(r1.Intn(100)) // Call the resulting `rand.Source` just like the functions on
fmt.Println(r1.Intn(100)) // the `rand` package.
fmt.Print(r1.Intn(100), ",") // Call the resulting `rand.Source` just like the
fmt.Print(r1.Intn(100)) // functions on the `rand` package.
fmt.Println()
r2 := rand.New(rand.NewSource(int64(1337))) // If you seed a source with the same number, it produces the
fmt.Println(r2.Intn(100)) // same sequence of random numbers.
fmt.Println(r2.Intn(100))
s2 := rand.NewSource(42) // If you seed a source with the same number, it
r2 := rand.New(s2) // produces the same sequence of random numbers.
fmt.Print(r2.Intn(100), ",")
fmt.Print(r2.Intn(100))
fmt.Println()
}
/*
$ go run rand.go
81,87
0.6645600532184904
5,87
5,87
*/