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Remove older file(s) from list based on create date

I have a set of folders containing log files. Each folder is named as the date the log files were created. I am getting the content of these folders within X days of today and storing the resulting FileInfo in a list. So it is possible to have file info with same file name X times, or less.
I need to keep only the latest files based on create date. So, if the list contains multiple entries where fi.FileName is the same, I need to keep the latest, based on fi.CreateDate and ditch the other instance(s).
I tried something like this but am messing up somewhere:
files = files.GroupBy(i => new {i.FileName, i.CreateDate}).Select(i => i.Last()).ToList();

You must change your sort code as follows:
files = files.OrderBy(f=>f.CreateDate).GroupBy(i => i.FileName).Select(i => i.Last()).ToList();
This one also will give the same result:
files =files.GroupBy(i => i.FileName).Select(i => i.OrderByDescending(f=>f.CreateDate).First()).ToList();

You can use such a method to get files to purge:
using System.IO;
using System.Linq;
using System.Collections.Generic;
static public IEnumerable<FileInfo> GetTraceFiles(bool sortByDateOnly = true)
{
string folder = "MyFullPath"; // Can be from some instance
string prefix = "MyTraceFile-"; // global vars
string extension = ".log"; // and config
var list = Directory.GetFiles(folder, prefix + "*" + extension)
.Where(f => !IsFileLocked(f))
.Select(f => new FileInfo(f))
.OrderBy(fi => fi.CreationTime);
return sortByDateOnly ? list : list.ThenBy(fi => fi.FullName);
}
And this clear method:
static public void ClearTraces(int retain = 0)
{
var list = GetTraceFiles();
if ( retain > 0 ) list = list.Take(list.Count() - retain + 1);
foreach ( var fileInfo in list )
try
{
File.Delete(fileInfo.FullName);
}
catch
{
}
}
Here it retains retain last files but you can adapt to add a Where clause to use a date before which to erase:
.Where(fi => fi.CreationTime < ...);
Also instead of using the file system creation date and time, it is possible to use the file pattern in case for example MyTrace-YYYY-MM-DD#HH-MM-SS...
IsFileLocked comes from:
Is there a way to check if a file is in use?

What's the best way to fiil list <string>?

I have a method, the input of which is a list of file addresses that I want to open this files and process it. this address contains the file extension. I know for sure that I have 3 file extensions (txt, xlsx, xls)
in the code pathWithFilesName it input list with file path;
then I want to send them to methods that will open and process them
pathWithFilesName.Add("ds.xlsx");
pathWithFilesName.Add("ds.txt");
var listExcel=new List<string>();
var listTxt= new List<string>();
var validExcelFileTypes = new List<string>{ ".xls", ".xlsx" };
foreach (var path in pathWithFilesName)
{
foreach (var valid in validExcelFileTypes)
{
if (path.EndsWith(valid))
{
listExcel.Add(path);
}
else
{
listTxt.Add(path);
}
}
}
this variant not optimal at all but work)
i know how take excel files on link
var list= (from path in pathWithFilesName from valid in validExcelFileTypes where path.EndsWith(valid) select path).ToList();
but with this approach I need then compare 2 lists. for example some kind of Intersect
what is the best way to make a sample?

Here is a variation using LinQ and lambda. It should not be more efficient not better or worse. It may be more readable.
The listExcel can be find that way :
var listExcel = pathWithFilesName.Where(path=>validExcelFileTypes.Any(ext=> path.EndsWith(ext)));
Enumerable.Any
Enumerable.Where
If you need both list in one go. You can group the source on the same condition:
var listGrp = pathWithFilesName.GroupBy(path=>validExcelFileTypes.Any(ext=> path.EndsWith(ext)));

You can use MoreLinQ Partition: "Partitions a sequence by a predicate,..".
var (listExcel, listTxt) = pathWithFilesName
.Partition(p =>
validExcelFileTypes.Any(ext => p.EndsWith(ext))
);
Under the hood it's just a GroupBy source code. Unrolled into a Named Tuple.
Live demo

Enumerate contents of specific folder DotNetZip, without child folders

Using Ionic.Zip
I wish to display the files or folders in a specific folder. I am using the SelectEntries method, but it unfortunately is filtering out the folders. Not what I was expecting using '*'.
ICollection<ZipEntry> selectEntries = _zipFile.SelectEntries("*",rootLocation)
If I follow an alternative approach:
IEnumerable<ZipEntry> selectEntries = _zipFile.Entries.Where(e => e.FileName.StartsWith(rootLocation))
I face two problems:
I have to switch '/' for '\' potentially.
I get all the subfolders.
Which is not desirable.
Anyone know why SelectEntries returns no folders, or am I misusing it?

I found a solution in my particular case. I think something about the way the Zipfile was constructed led to it appearing to have folders but none actually existed i.e. the following code yielded an empty list.
_zipFile.Entries.Where(e=>e.IsDirectory).AsList(); // always empty!
I used the following snippet to achieve what I needed. The regex is not as comprehensive as it should be but worked for all cases I needed.
var conformedRootLocation = rootLocation.Replace('\\','/').TrimEnd('/') + "/";
var pattern = string.Format(#"({0})([a-z|A-Z|.|_|0-9|\s]+)/?", conformedRootLocation);
var regex = new Regex(pattern);
return _zipFile.EntryFileNames.Select(e => regex.Match(e))
.Where(match => match.Success)
.Select(match => match.Groups[2].Value)
.Distinct()
.Select(f => new DirectoryResource
{
Name = f, IsDirectory = !Path.HasExtension(f)
})
.ToList();

C#: Get the 5 newest (last modified) files from a directory

Is there a way I can store the file location of the 5 last modified files from a directory using Array?
I am currently using the following codes below to get the last file:
DateTime lastHigh = new DateTime(1900,1,1);
string highDir;
foreach (string subdir in Directory.GetDirectories(path)){
DirectoryInfo fi1 = new DirectoryInfo(subdir);
DateTime created = fi1.LastWriteTime;
if (created > lastHigh){
highDir = subdir;
lastHigh = created;
}
}
I'll be using Array to send multiple files to an email address as attachment.
UPDATE
I am currently using the codes below to get the last modified files after 1 minute:
string myDirectory = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyPictures),
"Test Folder");
var directory = new DirectoryInfo(myDirectory);
DateTime from_date = DateTime.Now.AddMinutes(-1);
DateTime to_date = DateTime.Now;
var files = directory.GetFiles().Where(file => file.LastWriteTime >= from_date && file.LastWriteTime <= to_date);
I want to store to list of file names coming from files

Here's a general way to do this with LINQ:
Directory.GetFiles(path)
.Select(x => new FileInfo(x))
.OrderByDescending(x => x.LastWriteTime)
.Take(5)
.ToArray()
I suspect this isn't quite what you want, since your code examples seem to be working at different tasks, but in the general case, this would do what the title of your question requests.

It sounds like you want a string array of the full filepaths of all the files in a directory.
Given you already have your FileInfo enumerable, you can do this:
var filenames = files.Select(f => f.FullName).ToArray();
If you wanted just the filenames, replace FullName with Name.

While the answer Paul Phillips provided worked. It's worth to keep in mind that the
FileInfo.LastWriteTime & FileInfo.LastAccessTime do not always work. It depends on how the OS is configured or could be a caching issue.
.NET FileInfo.LastWriteTime & FileInfo.LastAccessTime are wrong
File.GetLastWriteTime seems to be returning 'out of date' value

How to check if filename contains substring in C#

I have a folder with files named
myfileone
myfiletwo
myfilethree
How can I check if file "myfilethree" is present.
I mean is there another method other than IsFileExist() method, i.e like filename contains substring "three"?

Substring:
bool contains = Directory.EnumerateFiles(path).Any(f => f.Contains("three"));
Case-insensitive substring:
bool contains = Directory.EnumerateFiles(path).Any(f => f.IndexOf("three", StringComparison.OrdinalIgnoreCase) > 0);
Case-insensitive comparison:
bool contains = Directory.EnumerateFiles(path).Any(f => String.Equals(f, "myfilethree", StringComparison.OrdinalIgnoreCase));
Get file names matching a wildcard criteria:
IEnumerable<string> files = Directory.EnumerateFiles(path, "three*.*"); // lazy file system lookup
string[] files = Directory.GetFiles(path, "three*.*"); // not lazy

If I understand your question correctly, you could do something like
Directory.GetFiles(directoryPath, "*three*")
or
Directory.GetFiles(directoryPath).Where(f => f.Contains("three"))
Both of these will give you all the names of all files with three in it.

I am not that familiar with IO but maybe this would work ? Requires using System.Linq
System.IO.Directory.GetFiles("PATH").Where(s => s.Contains("three"));
EDIT: Note that this returns array of strings.