在 C# 中读取位置未知的特定行

Question

我正在尝试编写一个程序以从 .txt 文件中读出用户组并将所述组放入列表框中。组列表的示例如下：

用户

-------------

第 1 组

Group2

Group3

[space]

下一个用户

每个用户都在未知数量的组中，这就是为什么有两个 space，只是为了将所有内容分开。

这是我目前的进度：

 private void Button_Click(object sender, RoutedEventArgs e) {
        //users.txt contains all users
        //in the same directory there are multiple lists with given groups
        StreamReader sr = new StreamReader("c:\ADHistory\users.txt", System.Text.Encoding.Default);
        string line = string.Empty;
        try {
            //Read the first line of text
            line = sr.ReadLine();
            //Continue to read until you reach end of file
            while (line != null) {
                listboxNames.Items.Add(line);
                //Read the next line
                line = sr.ReadLine();
            }

            //close the file
            sr.Close();
        }
        catch (Exception f)
        {
            MessageBox.Show(f.Message.ToString());
        }
        finally
        {
            //close the file
            sr.Close();
        }
    }

    private void listboxNames_SelectionChanged(object sender, SelectionChangedEventArgs e) {
        //as soon as you choose a user from the first list
        //you may choose a date to look at all groups the user is in.
        listboxDates.Items.Clear();
        DirectoryInfo dinfo = new DirectoryInfo(@"C:\ADHistory");
        FileInfo[] Files = dinfo.GetFiles("*.txt");

        //this adds all dates into the second listbox
        //and removes users.txt from the list.
        foreach (FileInfo file in Files) {
            listboxDates.Items.Add(file.Name);
        }
        for (int n = listboxDates.Items.Count - 1; n >= 0; --n)
        {
            string removelistitem = "users";
            if (listboxDates.Items[n].ToString().Contains(removelistitem))
            {
                listboxDates.Items.RemoveAt(n);
            }
            //this displays the user below the listboxes,
            //because of styling purposes
            string user = Convert.ToString(this.listboxNames.SelectedItem);
            labelName.Content = user;

        }
    }

    //here we have my main problem.
    //I can't find a solution to add the groups to the last listbox
    private void listboxDates_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        string user = Convert.ToString(labelName.Content);
        listboxGroups.Items.Clear();
        string path = "C:\ADHistory\";
        path += Convert.ToString(this.listboxDates.SelectedItem);

        foreach (string line in File.ReadLines(path))
        {
            if (line.Contains(user))
            {
                while (line != " ")
                {
                    listboxGroups.Items.Add(line);
                }
            }
        }
    }

我真的希望你能帮助我。

编辑

这个问题已经回答了，就不用再回答了。感谢所有评论:)

Answer 1

你的问题是，当找到用户所在的行时，你测试 if line == " " 而没有继续下一步，你的 while 循环应该立即退出

使用 for 循环而不是 for each。当您找到相同的用户行时，让您的 while 循环，并在 while 循环内用 ++ 增加循环变量并读取下一行。不要忘记在设置 line = fileLines[lineIndex]

之前检查字符串数组长度

因此，这是适合您的代码

string[] fileLines = File.ReadAllLines(path);

for (int lineIndex = 0; lineIndex < fileLines.Length; lineIndex++)
{
    string line = fileLines[lineIndex];
    if (line.Contains(user))
    {
        while(++lineIndex < fileLines.Length && (line = fileLines[lineIndex]) != " ")
        {
            listboxGroups.Items.Add(line);
        }
        break;
    }
}

但是，如果文件很大，您可能不想将所有行都读入内存，这是另一种适用于 File.ReadLines()

的方法

IEnumerator<string> fileLines = File.ReadLines(path).GetEnumerator();

while (fileLines.MoveNext())
{
    string line = fileLines.Current;
    if (line.Contains(user))
    {
        while (fileLines.MoveNext())
        {
            line = fileLines.Current;
            if (line == " ")
            {
                break;
            }
            listboxGroups.Items.Add(line);
        }
        break;
    }
}

在 C# 中读取位置未知的特定行

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