c# String Query - 获取最新的文件版本

Question

我正在编写一个表单应用程序，它显示 Datagridview 目录中的所有 PDF 文件。 现在文件名格式通常是12740-250-B-File Name（所以基本上是XXXXXX-XXX-X-XXXXXXX）。 所以第一个数字是项目号，破折号后面的第二个数字是序列号-字母是文件的修订版。

我想要一个按钮，按下时它会找到具有相同序列号的文件（XXXXX-Series No - Revision - XXXXXX）并显示最新的版本，它将是最大的字母，所以在 12763 之间-200-A-HelloWorld 和 12763-200-B-HelloWorld 我希望 12763-200-B-HelloWorld 成为我的查询结果。

这是我目前得到的：

private void button1_Click(object sender, EventArgs e)
{

}

private void button2_Click(object sender, EventArgs e)
{
    String[] files = Directory.GetFiles(@"M:\Folder Directory","*.pdf*", SearchOption.AllDirectories);
    DataTable table = new DataTable();
    table.Columns.Add("File Name");

    for (int i = 0; i < files.Length; i++)
    {
        FileInfo file = new FileInfo(files[i]);
        table.Rows.Add(file.Name);

    }
    dataGridView1.DataSource = table;
}

提前致谢。

注意： 最后，最新版本的文件将被插入到 Excel 电子表格中。

Answer 1

假设您的收藏是一个文件名列表，它是 Directory.GetFiles("");下面的 linq 将起作用。为了使下面的工作，您需要确定文件格式，因为拆分对特定文件格式非常敏感。

var seriesNumber = "200";
var files = new List<string> { "12763-200-A-HelloWorld", "12763-200-B-HelloWorld" };

var matching = files.Where(x => x.Split('-')[1] == seriesNumber)
                    .OrderByDescending(x => x.Split('-')[2])
                    .FirstOrDefault();

结果：

匹配：“12763-200-B-HelloWorld”

Answer 2

您可以尝试以下方法：

string dirPath = @"M:\Folder Directory";
string filePattern = "*.pdf";

DirectoryInfo di = new DirectoryInfo(dirPath);
FileInfo[] files = di.GetFiles(filePattern, SearchOption.AllDirectories);

Dictionary<string, FileInfo> matchedFiles = new Dictionary<string, FileInfo>();

foreach (FileInfo file in files)
{
    string filename = file.Name;
    string[] seperatedFilename = filename.Split('-');

    // We are assuming that filenames are consistent
    // As such,
    // the value at seperatedFilename[1] will always be Series No
    // the value at seperatedFilename[2] will always be Revision
    // If this is not the case in every scenario, the following code should expanded to allow other cases
    string seriesNo = seperatedFilename[1];
    string revision = seperatedFilename[2];

    if (matchedFiles.ContainsKey(seriesNo))
    {
        FileInfo matchedFile = matchedFiles[seriesNo];
        string matchedRevision = matchedFile.Name.Split('-')[2];

        // Compare on the char values - https://docs.microsoft.com/en-us/dotnet/api/system.string.compareordinal?view=netframework-4.7.2
        // If the value is int, then it can be cast to integer for comparison
        if (String.CompareOrdinal(matchedRevision, seriesNo) > 0)
        {
            // This file is higher than the previous
            matchedFiles[seriesNo] = file;
        }
    } else
    {
        // Record does not exist - so its is added by default
        matchedFiles.Add(seriesNo, file);
    }
}

// We have a list of all files which match our criteria
foreach (FileInfo file in matchedFiles.Values)
{
    // TODO : Determine if the directory path is also required for the file
    Console.WriteLine(file.FullName);
}

它将文件名拆分为组成部分，并比较系列名称匹配的修订版；将结果存储在字典中以供以后进一步处理。

Answer 3

在我看来，这似乎是使用字典的好时机！您可以尝试以下方法：

        String[] files = new string[5];

        //group of files with the same series number
        files[0] = "12763-200-A-HelloWorld";
        files[1] = "12763-200-X-HelloWorld";
        files[2] = "12763-200-C-HelloWorld";

        //another group of files with the same series number
        files[3] = "12763-203-C-HelloWorld";
        files[4] = "12763-203-Z-HelloWorld";

        //all the discting series numbers, since split will the de second position of every string after the '-'
        var distinctSeriesNumbers = files.Select(f => f.Split('-')[1]).Distinct();
        Dictionary<String, List<String>> filesDictionary = new Dictionary<string, List<String>>();

         //for each series number, we will try to get all the files and add them to dictionary
        foreach (var serieNumber in distinctSeriesNumbers)
        {
            var filesWithSerieNumber = files.Where(f => f.Split('-')[1] == serieNumber).ToList();
            filesDictionary.Add(serieNumber, filesWithSerieNumber);
        }

        List<String> listOfLatestSeries = new List<string>();

        //here we will go through de dictionary and get the latest file of each series number
        foreach (KeyValuePair<String, List<String>> entry in filesDictionary)
        {
            listOfLatestSeries.Add(entry.Value.OrderByDescending(d => d.Split('-')[2]).First());
        }

        //now we have the file with the last series number in the list 
        MessageBox.Show(listOfLatestSeries[0]); //result : "12763-200-X-HelloWorld"
        MessageBox.Show(listOfLatestSeries[1]); //result : "12763-203-Z-HelloWorld";