Retrieve File Names from a folder while new files are being created by other application

Question

I have a task to process files from a folder using C#, the naming convention of the files is like this:

0000001.log
0000002.log
....
00nnnnn.log

Given a parameter x, all the files with the name smaller than x will be processed. After processing, the file will be deleted.

At the same time, another application will constantly adding log files to this folder, with an incremental number.

I know I can use GetFiles or EnumerateFiles & linq in C# to filter the files I need.

If I understand correctly, these two method will load all the file names into memory first, and then filter out the ones I need.

Since nnnn is quite a large number, I think it will be more efficient if I have a way to retrieve only the file names I need, ie x number of files, without loading all file names

Is this possible?

Answer 1

You can use file system watcher to receive a notification on a new file creation:

System.IO.FileSystemWatcher m_Watcher = new System.IO.FileSystemWatcher(); 
m_Watcher.Path = folderPath; 
m_Watcher.Filter = strFilter; 
m_Watcher.NotifyFilter = NotifyFilters.LastAccess | 
                     NotifyFilters.LastWrite | 
                     NotifyFilters.FileName | 
                     NotifyFilters.DirectoryName;

m_Watcher.Changed += new FileSystemEventHandler(OnChanged);
m_Watcher.Created += new FileSystemEventHandler(OnChanged);

While strFilter is the filter for the file names for example: "*.txt";

For further information https://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher(v=vs.110).aspx

Answer 2

您可以进行for迭代并在其中添加if条件。如果条件为true，则将其放到该文件中。