Read space separated integers from stdin into int slice

I'm trying to read from stdin two lines of an unknown number of space-separated integers. I would like to store each lines ints into their own int slice.

For example, my input may look like this:

1 2 3
4 5 6

and I want to read this into two []int:

[1,2,3]
[4,5,6]

This is what I have so far. scanner.Scan() is giving me the line, but I'm not sure how to convert that into a []int:

package main
import (
    "fmt"
    "os"
    "bufio"
)

func main() {
    var firstLine []int
    var secondLine []int
    
    scanner := bufio.NewScanner(os.Stdin)
    for scanner.Scan() {
        t := scanner.Text()
    }
}

For example,

numbers.go:

package main

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

func numbers(s string) []int {
	var n []int
	for _, f := range strings.Fields(s) {
		i, err := strconv.Atoi(f)
		if err == nil {
			n = append(n, i)
		}
	}
	return n
}

func main() {
	var firstLine, secondLine []int
	scanner := bufio.NewScanner(os.Stdin)
	for i := 1; i <= 2 && scanner.Scan(); i++ {
		switch i {
		case 1:
			firstLine = numbers(scanner.Text())
		case 2:
			secondLine = numbers(scanner.Text())
		}
	}
	fmt.Println(firstLine)
	fmt.Println(secondLine)
}

Output:

$ go run numbers.go
1 2 3
4 5 6
[1 2 3]
[4 5 6]
$

If you are looking for code to read input to solve problems in hackathons, here is your best solution

package main

import (
	"bufio"
	"os"
	"fmt"
)

func main() {

	reader := bufio.NewReader(os.Stdin)
	
	a:= read(reader,100000)

	fmt.Println(a)
}

func read (reader *bufio.Reader, n int)([]uint32) {
	
	a := make([]uint32, n)
	for i:=0; i<n; i++ {
		fmt.Fscan(reader, &a[i])
	}
	
	return a
}

So, this is what I ended up doing. There is likely a more idiomatic way of solving it, though.

package main
import (
    "fmt"
    "os"
    "bufio"
    "strings"
    "strconv"
)

func main() {
        
    scanner := bufio.NewScanner(os.Stdin)
    
    scanner.Scan()
    parts := strings.Split(scanner.Text(), " ")
    lineOne := createIntSlice(parts)
    
    scanner.Scan()
    parts = strings.Split(scanner.Text(), " ")
    lineTwo := createIntSlice(parts)
    
    fmt.Println(lineOne)
    fmt.Println(lineTwo)
}

func createIntSlice(nums []string) []int {
    var r []int
    for _, v := range nums {
        i, _ := strconv.Atoi(v)
        r = append(r, i)
    }
    return r
}

For another option, you can implement fmt.Scanner:

package main

import (
   "bytes"
   "fmt"
)

type slice struct {
   tok []int
}

func (s *slice) Scan(state fmt.ScanState, verb rune) error {
   tok, err := state.Token(false, func(r rune) bool { return r != '\n' })
   if err != nil { return err }
   if _, _, err := state.ReadRune(); err != nil {
      if len(tok) == 0 {
         panic(err)
      }
   }
   b := bytes.NewReader(tok)
   for {
      var d int
      _, err := fmt.Fscan(b, &d)
      if err != nil { break }
      s.tok = append(s.tok, d)
   }
   return nil
}

func main() {
   var s slice
   fmt.Scan(&s)
   fmt.Println(s.tok) // [1 2 3]
}

https://golang.org/pkg/fmt#Scanner

A simpler way to Handle taking space separated integers in a slice !!

func StringToIntSlice(inputSequence string) []int {
	var slicedIntegerSequence = []int{}
	var splittedSequence = strings.Split(inputSequence, " ")
	for _, value := range splittedSequence {
		intValue, _ := strconv.Atoi(value)
		slicedIntegerSequence = append(slicedIntegerSequence, intValue)
	}
	return slicedIntegerSequence
}


func main() {

	var inputSequence string
	var convertedSliceOfIntegers = []int{}
	scanner := bufio.NewScanner(os.Stdin)

	fmt.Println("Enter a Sequence of 10 Integers separated by spaces:")
	scanner.Scan()
	inputSequence = scanner.Text()
	convertedSliceOfIntegers = StringToIntSlice(inputSequence)
}

package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
)

// You receive a string as parameter
// List receives N As a string slice
// Returns N as a string slice
func number(n string) []string {
	list := strings.Fields(n)

	return list
}

func main() {
	scanner := bufio.NewScanner(os.Stdin) //Receiving user data ...

	list := make([][]string, 0) // Declare a slice to receive other slices inside it

	for scanner.Scan() { // Scrolls all typed data to true

		// If the user does not type anything, that is, if he presses Enter an interrupt will occur
		if scanner.Text() == "" {
			break
		} else {
			list = append(list, number(scanner.Text())) // Adding the slice inside list
		}
	}

	fmt.Println(list) // print list
}

All data is going and returning as string, but you can convert them to integers easily.