How to remove special char in golang when reading file?

huangapple
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英文:

How to remove special char in golang when reading file?

问题

我有一个文件，内容如下：
每行代表一个网站

  1. 1 www.google.com$
  2. 2 www.apple.com$
  3. 3 www.facebook.com$

我在golang中这样读取它：

  1. type ListConf struct {
  2.     File  string
  3.     Datas map[string]struct{}
  4. }
  6. func loadListConf(conf *ListConf, path string) {
  7.     file, err := os.Open(path + "/" + conf.File)
  8.     if err != nil {
  9. 	    fmt.Println("加载配置文件" + conf.File + "出错：" + err.Error())
  10. 	    return
  11.     }
  12.     defer file.Close()
  13.     conf.Datas = make(map[string]struct{})
  14.     buf := bufio.NewReader(file)
  15.     end := false
  16.     for !end {
  17. 	    line, err := buf.ReadString('\n')
  18. 	    if err != nil {
  19. 		    if err != io.EOF {
  20. 			    fmt.Println("加载配置文件" + conf.File + "出错：" + err.Error())
  21. 			    return
  22. 		    } else {
  23. 			    end = true
  24. 		    }
  25. 	    }
  26. 	    item := strings.Trim(line, "\n")
  27. 	    if item == "" {
  28. 		    continue
  29. 	    }
  30. 	    conf.Datas[item] = struct{}{}
  31.     }
  32. }

但是当我在map中搜索"www.google.com"这样的键时，显示map中没有"www.google.com"。

  1. website := "www.google.com"
  2. if _, ok := conf.Datas[website]; ok {
  3.     fmt.Printf("%s在map中。", website)
  4. } else {
  5.     fmt.Printf("%s不在map中。", website)
  6. }

它打印出"www.google.com不在map中"。
我发现在map中的每个键的末尾有一个^M，我的问题是如何去除^M字符？

  1. www.google.com^M
  2. www.apple.com^M
  3. www.facebook.com^M
英文:

I have a file like this:
Each line represents a Website

  1. 1 www.google.com$
  2. 2 www.apple.com$
  3. 3 www.facebook.com$

I read it in golang like this:

  1. type ListConf struct {
  2.     File  string
  3.     Datas map[string]struct{}
  4. }
  6. func loadListConf(conf *ListConf, path string) {
  7.     file, err := os.Open(path + "/" + conf.File)
  8.     if err != nil {
  9. 	    fmt.Println("Load conf " + conf.File + " error: " + err.Error())
  10. 	    return
  11.     }
  12.     defer file.Close()
  13.     conf.Datas = make(map[string]struct{})
  14.     buf := bufio.NewReader(file)
  15.     end := false
  16.     for !end {
  17. 	    line, err := buf.ReadString('\n')
  18. 	    if err != nil {
  19. 		    if err != io.EOF {
  20. 			    fmt.Println("Load conf " + conf.File + " error: " + err.Error())
  21. 			    return
  22. 		    } else {
  23. 			    end = true
  24. 		    }
  25. 	    }
  26. 	    item := strings.Trim(line, "\n")
  27. 	    if item == "" {
  28. 		    continue
  29. 	    }
  30. 	    conf.Datas[item] = struct{}{}
  31.     }
  32. }

But when I search key such like "www.google.com" in the map, it shows that there is not a "www.google.com" in the map.

  1. website := "www.google.com"
  2. if _, ok := conf.Datas[website]; ok {
  3.     fmt.Printf("%s is in the map.", website)
  4. } else {
  5.     fmt.Printf("%s is not in the map.", website)
  6. }

It print "www.google.com is not in the map".
I found that a ^M in the end of each key in the map, my question is how can I remove the ^M character?

  1. www.google.com^M
  2. www.apple.com^M
  3. www.facebook.com^M

答案1

得分: 4

在Windows上，文本文件的默认行分隔符是由两个字符组成的序列：\r\n。你在字符串中看到的^M字符代表的是\r。

bufio.Scanner可以以与平台无关的方式处理将输入拆分为行：

  1. scanner := bufio.NewScanner(file)
  2. for scanner.Scan() {
  3.     fmt.Println(scanner.Text())
  4. }
  5. if err := scanner.Err(); err != nil {
  6.     fmt.Fprintln(os.Stderr, "从文件中读取时出错：", err)
  7. }
英文:

The default line separator in text files on Windows is a sequence of two characters: \r\n. ^M character that you see in your strings is \r.

bufio.Scanner can take care of splitting the input into lines in a platform independent way:

  1. scanner := bufio.NewScanner(file)
  2. for scanner.Scan() {
  3. 	fmt.Println(scanner.Text())
  4. }
  5. if err := scanner.Err(); err != nil {
  6. 	fmt.Fprintln(os.Stderr, "error reading from the file:", err)
  7. }

答案2

得分: 2

不太优雅，但是你可以使用以下代码从字符串末尾删除\r：

  1. line, err := buf.ReadString('\n')
  2. line = strings.TrimRight(line, "\r")

它会删除多个\r（^M），如果没有\r，则不会有任何操作。

英文:

Less elegant but...

You can strip the \r from the end of the string with:

  1.         line, err := buf.ReadString('\n')
  2.         line = strings.TrimRight(line, "\r")

It will remove multiple \r (^M) and is a no-op if there are none.

huangapple
  • 本文由 发表于 2016年2月1日 11:11:36
  • 转载请务必保留本文链接：https://go.coder-hub.com/35122482.html
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