如何结束控制台中的`scanner.Scan`循环以获取golang？

Question

I have two (or potentially more) lines of input that I would like the program to take. eg.

1 2 3 4
5 6 7 8

According to the official doc, using

for scanner.Scan() {
}

will cause infinite lines to be scan until it reach EOF or error, are there other functions that will take two lines of input instead?

Answer 1

It's traditional to end user input from stdin with an empty (zero length) line. For example,

package main

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

func main() {
    snr := bufio.NewScanner(os.Stdin)
    enter := "Enter a line of data:"
    for fmt.Println(enter); snr.Scan(); fmt.Println(enter) {
        line := snr.Text()
        if len(line) == 0 {
            break
        }
        fields := strings.Fields(line)
        fmt.Printf("Fields: %q
", fields)
    }
    if err := snr.Err(); err != nil {
        if err != io.EOF {
            fmt.Fprintln(os.Stderr, err)
        }
    }
}

Output:

$ go run data.go
Enter a line of data:
1 2 3 4
Fields: ["1" "2" "3" "4"]
Enter a line of data:
5 6 7 8
Fields: ["5" "6" "7" "8"]
Enter a line of data:

$