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57 lines
1.5 KiB
Go
57 lines
1.5 KiB
Go
// Go's `math/rand` package provides
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// [pseudorandom number](http://en.wikipedia.org/wiki/Pseudorandom_number_generator)
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// generation.
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package main
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import (
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"fmt"
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"math/rand"
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"time"
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)
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func main() {
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// For example, `rand.Intn` returns a random `int` n,
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// `0 <= n < 100`.
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fmt.Print(rand.Intn(100), ",")
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fmt.Print(rand.Intn(100))
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fmt.Println()
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// `rand.Float64` returns a `float64` `f`,
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// `0.0 <= f < 1.0`.
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fmt.Println(rand.Float64())
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// This can be used to generate random floats in
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// other ranges, for example `5.0 <= f' < 10.0`.
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fmt.Print((rand.Float64()*5)+5, ",")
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fmt.Print((rand.Float64() * 5) + 5)
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fmt.Println()
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// The default number generator is deterministic, so it'll
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// produce the same sequence of numbers each time by default.
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// To produce varying sequences, give it a seed that changes.
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// Note that this is not safe to use for random numbers you
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// intend to be secret, use `crypto/rand` for those.
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s1 := rand.NewSource(time.Now().UnixNano())
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r1 := rand.New(s1)
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// Call the resulting `rand.Rand` just like the
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// functions on the `rand` package.
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fmt.Print(r1.Intn(100), ",")
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fmt.Print(r1.Intn(100))
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fmt.Println()
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// If you seed a source with the same number, it
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// produces the same sequence of random numbers.
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s2 := rand.NewSource(42)
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r2 := rand.New(s2)
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fmt.Print(r2.Intn(100), ",")
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fmt.Print(r2.Intn(100))
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fmt.Println()
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s3 := rand.NewSource(42)
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r3 := rand.New(s3)
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fmt.Print(r3.Intn(100), ",")
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fmt.Print(r3.Intn(100))
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}
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