Golang: Read ints from stdin until EOF while reporting format errors

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英文:

Golang: Read ints from stdin until EOF while reporting format errors

问题

nums := make([]int, 0)
{
var d int
for {
_, err := fmt.Scan(&d)
if err != nil {
break
}

  1. nums = append(nums, d)
  2. }

}

这段代码用于从标准输入中读取整数。但是如果标准输入看起来像 1 2 3 f4 5nums 最终会变成 [1 2 3],而不报告任何错误。

如何处理这种情况最好?(即,我希望从 fmt.Scan 中获得 EOF 时,循环会静默退出,但其他所有错误都应该报告)。

编辑:我只需要 io.EOF -- 我在 http://golang.org/pkg/fmt/ 上没有找到这个文档

nums := make([]int, 0)
{
var d int
for {
_, err := fmt.Scan(&d)
if err != nil {
if err != io.EOF {
log.Fatal(err)
}
break
}

  1. nums = append(nums, d)
  2. }

}

英文:
  1. nums := make([]int, 0)
  2. {
  3. var d int
  4. for {
  5. _, err := fmt.Scan(&d)
  6. if err != nil {
  7. break
  8. }
  9. nums = append(nums, d)
  10. }
  11. }

This works to read in ints from stdin. But if stdin looks like 1 2 3 f4 5, nums will end up being [1 2 3] without reporting any error.

What's the best way of handling this? (Ie, I want EOF from fmt.Scan to silently exit the loop, but all other errors should be reported).

edit: io.EOF was all I needed -- I hadn't found that documented at http://golang.org/pkg/fmt/

  1. nums := make([]int, 0)
  2. {
  3. var d int
  4. for {
  5. _, err := fmt.Scan(&d)
  6. if err != nil {
  7. if err != io.EOF {
  8. log.Fatal(err)
  9. }
  10. break
  11. }
  12. nums = append(nums, d)
  13. }
  14. }

答案1

得分: 16

你可以这样做-当你得到一个错误的数字时,读取下一个以空格分隔的内容。设置一个标志或在出现错误时保留一个错误列表,在最后报告这些错误。

(Playground链接)

  1. package main
  2. import (
  3. "bytes"
  4. "fmt"
  5. "io"
  6. )
  7. func main() {
  8. in := bytes.NewBufferString("1 2 3 f4 5")
  9. nums := make([]int, 0)
  10. var d int
  11. for i := 0; i < 10; i++ {
  12. _, err := fmt.Fscan(in, &d)
  13. if err == io.EOF {
  14. break
  15. }
  16. if err != nil {
  17. var s string
  18. _, err := fmt.Fscan(in, &s)
  19. if err != nil {
  20. break
  21. }
  22. fmt.Printf("跳过错误的数字:%q\n", s)
  23. } else {
  24. nums = append(nums, d)
  25. }
  26. }
  27. fmt.Printf("nums = %v\n", nums)
  28. }

输出结果为:

  1. 跳过错误的数字:"f4"
  2. nums = [1 2 3 5]
英文:

You could do it like this - when you get a bad number, read the next space separated thing. Set a flag or on an error or keep a list of the errors to report at the end.

(Playground link)

  1. package main
  2. import (
  3. &quot;bytes&quot;
  4. &quot;fmt&quot;
  5. &quot;io&quot;
  6. )
  7. func main() {
  8. in := bytes.NewBufferString(&quot;1 2 3 f4 5&quot;)
  9. nums := make([]int, 0)
  10. var d int
  11. for i := 0; i &lt; 10; i++ {
  12. _, err := fmt.Fscan(in, &amp;d)
  13. if err == io.EOF {
  14. break
  15. }
  16. if err != nil {
  17. var s string
  18. _, err := fmt.Fscan(in, &amp;s)
  19. if err != nil {
  20. break
  21. }
  22. fmt.Printf(&quot;Skipping bad number: %q\n&quot;, s)
  23. } else {
  24. nums = append(nums, d)
  25. }
  26. }
  27. fmt.Printf(&quot;nums = %v\n&quot;, nums)
  28. }

Which prints

  1. Skipping bad number: &quot;f4&quot;
  2. nums = [1 2 3 5]

huangapple
  • 本文由 发表于 2013年10月11日 02:11:44
  • 转载请务必保留本文链接:https://go.coder-hub.com/19303137.html
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