How to use fmt.Sscan to parse integers into an array?

I'm trying to scan a list of integers from a string into an array (or alternatively, a slice)

package main

import "fmt"

func main() {
	var nums [5]int
    n, _ := fmt.Sscan("1 2 3 4 5", &nums)  // doesn't work
    fmt.Println(nums)
}

What do I need to pass as second argument to Sscan in order for this to work?

I know I could pass nums[0], nums[1] ... etc., but I'd prefer a single argument.

I don't think this is possible as a convenient one-liner. As Sscan takes ...interface{}, you would need to pass slice of interfaces as well, hence converting your array first:

func main() {
	var nums [5]int

	// Convert to interfaces
	xnums := make([]interface{}, len(nums))
	for n := range nums {
		xnums[n] = &nums[n]
	}

	n, err := fmt.Sscan("1 2 3 4 5", xnums...)
	if err != nil {
		fmt.Printf("field %d: %s\n", n+1, err)
	}

	fmt.Println(nums)
}

http://play.golang.org/p/1X28J7JJwl

Obviously you could mix different types in your interface array, so it would make the scanning of more complex string easier. For simply space-limited integers, you might be better using strings.Split or bufio.Scanner along with strconv.Atoi.

To allow this to work on more than just hard-coded strings, it's probably better to use a bufio.Scanner, and an io.Reader interface to do this:

package main

import (
	"bufio"
	"fmt"
	"io"
	"strconv"
	"strings"
)

func scanInts(r io.Reader) ([]int, error) {
	s := bufio.NewScanner(r)
	s.Split(bufio.ScanWords)
	var ints []int
	for s.Scan() {
		i, err := strconv.Atoi(s.Text())
		if err != nil {
			return ints, err
		}
		ints = append(ints, i)
	}
	return ints, s.Err()
}

func main() {
	input := "1 2 3 4 5"
	ints, err := scanInts(strings.NewReader(input))
	if err != nil {
		fmt.Println(err)
	}
	fmt.Println(ints)
}

Produces:

>[1 2 3 4 5]

Playground

Unless you're trying to use Sscann specifically you can also try this as an alternative:

• split the input string by spaces
• iterate the resulting array
• convert each string into an int
• store the resulting value into an int slice

Like this:

package main

import (
	"fmt"
	"strconv"
	"strings"
)

func main() {

	nums := make([]int, 0)
	for _, s := range strings.Split("1 2 3 4 5", " ") {
		i, e := strconv.Atoi(s)
		if e != nil {
			i = 0 // that was not a number, default to 0
		}
		nums = append(nums, i)
	}
	fmt.Println(nums)
}

http://play.golang.org/p/rCZl46Ixd4