C＃文件列表名称比较

Question

I have a simple but yet very hard task for my coding skills.

Basically I have a task to parse all file names in specific folder (this executed ok) but then I have to compare those file names and choose the one with the latest (biggest) number in a specific part of file name. An example:

0074-105-NVK.1.p7.ver.1.pdf
0074-105-NVK.1.p7.ver.2.pdf
0074-105-NVK.1.p7.ver.3.pdf

The part that interests me is the one where " ver.1 " from this the program should choose the highest one and remove other files. And I really don't know how to implement this filename comparison.

Answer 1

I suggest extracting version info with a help of regular expressions and ordering by this version:

  string[] files = new string[] {
     "0074 - 105 - NVK.1.p7.ver.1.pdf",
     "0074 - 105 - NVK.1.p7.ver.2.pdf",
     "0074 - 105 - NVK.1.p7.ver.3.pdf", };

  string pattern = @"ver\.(?<version>[0-9]+(\.[0-9]+)*)[^0-9]+$";

  var result = files
    .Select(file => new {
      name = file,
      ver = new Version(Regex.Match(file, pattern).Groups["version"].Value + ".0")
    })
    .OrderByDescending(item => item.ver)
    .Select(item => item.name)
    .FirstOrDefault();

Answer 2

You could use the following to get all file names as:

string[] fileNames = Directory.GetFiles(@"d:\Dir\", "*.pdf").ToList();
List<string> nameOnly = new List<string>();
List<KeyValuePair<string, string>> bind = new List<KeyValuePair<string, string>>();

once you have all the file names in a list then you can exclude the extension as:

foreach(var item in fileNames)
{ 
    var x = Regex.Match(item, @".*(?=\.)").Value;
    nameOnly.Add(x);
}

Just for binding each name with its file name:

foreach(var item in nameOnly)
{ 
    var x = Regex.Match(item, @".*(?=\.)").Value;
    bind.Add(new KeyValuePair<string, string>(x,item));
}

And you can get the final file name with max number as:

var max = bind.OrderBy(x => x.Key);
var fileName = max.LastOrDefault().Value;

Answer 3

It can be done nicely with a single lambda row:

var s1 = "0074-105-NVK.1.p7.ver.1.pdf";
var s2 = "0074-105-NVK.1.p7.ver.2.pdf";
var s3 = "0074-105-NVK.1.p7.ver.3.pdf";
var arr = new[] {s1, s2, s3};
var latestVer = arr.OrderBy(s => int.Parse(s.Split('.')[s.Split('.').Length - 2])).Last();

Answer 4

You should have filenames in array or list:

var fileNames = new List<string>();
// fill list with proper file names

Regading you sample you can sort this list (assume that only ver.x can change):

list.Sort(); // you can use parametrized method which sort by part of string

You can also use SortedList (that you have all sorted automatically):

var fileNames = new SortedList<string>();
fileNames.Add(fileName.Substring(18), fileName);

Or you can use Linq:

var sorted = fileNames.OrderBy(item => item.Substring(18)); // in that case you can use different parts of file name)

Answer 5

Try this code:

       string[] files = new string[] {
                         "0074 - 105 - NVK.1.p7.ver.1.pdf",
                         "0074 - 105 - NVK.1.p7.ver.11.pdf",
                         "0074 - 105 - NVK.1.p7.ver.2.pdf", };


        var result = files.Select(f => new
        {
            name = f,
            ver = int.Parse((f.Substring(f.IndexOf(".ver") + 1).Split('.')[1]))
        })
          .OrderByDescending(x => x.ver)
          .Select(x => x.name)
          .FirstOrDefault();