Question

我有一个包含文件的目录 1.TXT 2.txt 3.txt

我怎样才能获得.txt文件名目录中的最高编号？

继承人我试过的事情

  DirectoryInfo d = new DirectoryInfo(@"C:\Users\Public\BotMakerLoggerSite\Logs\" + token + @"\");
            int highest = 0;
                 foreach (var file in d.GetFiles(" *.txt"))
                 {
                     string a = file.Name.Replace(".txt", "");
                     int b = Convert.ToInt32(a);
                     if (b >= highest)
                     {
                         highest = b;
                     }

               }
            try
            {
                t = File.ReadAllText(@"C:\Users\Public\BotMakerLoggerSite\Logs\" + token + @"\" + highest + ".txt");

            }
            catch
            {
                Console.WriteLine("Error");
            }
            File.WriteAllText(@"C:\Users\Public\BotMakerLoggerSite\Logs\" + token + @"\" + highest + ".txt", t + Environment.NewLine + e.Source + " | " + DateTime.Now + " | " + e.Severity + " : " + e.Message + "=" + highest);

Answer 1

这应该有所帮助。它使用正则表达式来提取文件名的数字部分;在这种情况下，它将在文件的开头查找数字，这似乎是您想要的。如果它类似于“my51st.txt”，它将不会返回51.正则表达式部分是行：

Match m = Regex.Match(name, "\\d+");

其中d +表示在字符串的开头提取一个或多个数字。

以下是代码：

        var fileNames = Directory.GetFiles(targetDirectory);
        var numberList = new List<int>();
        int number;

        foreach (var name in fileNames) {
            Match m = Regex.Match(name, "\\d+"); // this gets the number at beginning of filename
            var isNumber = Int32.TryParse(m.ToString(), out number);

            if(isNumber)
                numberList.Add(number);
        }

        var highest = numberList.OrderByDescending(x => x).FirstOrDefault();

编辑：重构为更有效的代码，不构建整个数组，然后得到最高的数字。还使用了来自C＃7的变量声明：

        var fileNames = Directory.GetFiles(targetDirectory);
        int? highest = null;

        foreach (var name in fileNames) {
            var m = Regex.Match(name, "^\\d+"); // this gets the number at beginning of filename
            Int32.TryParse(m.ToString(), out int number);

            if (number > (highest ?? 0))
                highest = number;
        }

        // The string 'result' will either contain the number or the message depending on whether it is still null or not.
        var result = (highest?.ToString() ?? "No Number Found");

Answer 2

我会用这种方法：

Func<string, int?> tryParse = x =>
{
    int r;
    if (int.TryParse(x, out r))
    {
        return r;
    }
    return null;
};

int highest =
    new DirectoryInfo(@"C:\Users\Public\BotMakerLoggerSite\Logs\" + token + @"\")
        .GetFiles()
        .Select(x => Path.GetFileNameWithoutExtension(x.Name))
        .Select(x => tryParse(x))
        .Where(x => x.HasValue)
        .Select(x => x.Value)
        .DefaultIfEmpty(0)
        .Max();

在c＃中获取最大数量的.txt文件

2 个答案: