CODEWITHSUNDEEP
go
Indu Pillai
Indu Pillai

Reputation: 377

Why the following Golang code doesn't run?

This code runs and gives a random number from 0 to 999:

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {
    rand.Seed(time.Now().UnixNano())
    fmt.Println(rand.Intn(999))
}

But the following code refuses to run and gives an error

Code:

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {
    r := rand.Seed(time.Now().UnixNano())
    fmt.Println(r.Intn(999))
}

Error message:

rand.Seed(time.Now().UnixNano()) used as value

Note: I'm new to stackOverflow, so if the question isn't according to the rules or standards, please forgive me.

Upvotes: 0

Views: 479

Answers (3)

Marco
Marco

Reputation: 2324

rand.Seed “sets up” rand.Intn, if you will. When you call rand.Seed, it creates a seed that can be used later with rand.Intn. rand.Intn returns a value, so

rand.Seed(time.Now().UnixNano())
fmt.Println(rand.Intn(999))

works. But since rand.Seed does not return a value, calling rand.Intn on it returns an error.

Upvotes: 0

Bulat Zamalutdinov
Bulat Zamalutdinov

Reputation: 11

From godoc

Seed uses the provided seed value to initialize the generator to a deterministic state. Seed should not be called concurrently with any other Rand method.

That means, that it set some seed for generating random numbers and don't return anything, but you tried to use it as some value

Upvotes: 1

Ankur
Ankur

Reputation: 33637

rand.Seed doesn't return any value, its a void function.

Upvotes: 3

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