C＃如何在不使用Directory.GetFiles（）方法的情况下遍历文件列表

Question

I have several security cameras that upload pictures to my ftp server. Some of these cams conveniently create subfolders at the start of a new day in the format "yyyymmdd". This is great and makes it easy to maintain/delete older pictures by a particular day. Other cams aren't so nice and just dump pictures in a giant folder, making deletion difficult.

So I am writing a C# windows form program to go to a specific folder (source folder) using FolderBrowserDialog and I name a target folder also using FBD. I was using the standard process to iterate through a file list using a string array filled via Directory.GetFiles() method. I use the file's Creation Date to create a subfolder if it doesn't exist. In either case I move the file to that date based subfolder. It works great while testing with small numbers of files.

Now I'm ready to test against real data and I'm concerned that with some folders having thousands of files, I'm going to have many issues with memory and other problems. How well can a string array handle such huge volumes of data? Note one folder has over 28,000 pictures. Can a string array handle such a large number of FileInfo objects?

My question then is how can I iterate through a list of files in a given folder without having to use a string array and Directory.GetFiles() method? I'm open to any thoughts though I do want to use c# in a windows form environment. I have an added feature that lets me delete pictures older than a given date instead of moving them.

Many thanks!

Answer 1

You'll be just fine with thousands of file names. You might have a problem with millions, but thousands isn't a big deal for C#. You may have a performance issue just because of how NTFS works, but if so there's nothing you can do about that in C#; it's a problem inherent in the file system.

However, if you really want to pick at this, you can do a little better by using Directory.EnumerateFileSystemInfos() . This method has two benefits over GetFiles() :

1. It loads the file name and creation date in one disk access, instead of two.
2. It allows you to work with an IEnumerable instead of an array, such that you only need memory for one file record at a time.