CODEWITHSUNDEEP
arrayspointersgoslice
Hongseok Yoon
Hongseok Yoon

Reputation: 3318

Read numbers from os.Stdin into array or slice in Go

I can read multiple numbers using multiple variables like bellow.

numbers := make([]int, 2)
fmt.Fscan(os.Stdin, &numbers[0], &numbers[1])

Can I use numbers itself not as separated shape to make it simpler?

numbers := make([]int, 2)
fmt.Fscan(os.Stdin, &numbers) // just an example, got error

Upvotes: 6

Views: 2818

Answers (1)

icza
icza

Reputation: 417592

The fmt package does not handle scanning slices, but you can create a utility function which packs the addresses of all the elements:

func packAddrs(n []int) []interface{} {
    p := make([]interface{}, len(n))
    for i := range n {
        p[i] = &n[i]
    }
    return p
}

And using this, you can scan a whole slice like this:

numbers := make([]int, 2)
n, err := fmt.Fscan(os.Stdin, packAddrs(numbers)...)
fmt.Println(numbers, n, err)

Testing it with fmt.Sscan():

numbers := make([]int, 5)
n, err := fmt.Sscan("1 3 5 7 9", packAddrs(numbers)...)
fmt.Println(numbers, n, err)

Output (try it on the Go Playground):

[1 3 5 7 9] 5 <nil>

Upvotes: 4

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