如何从C＃中的文件夹获取第一个文件名

Question

I need to get the first file name from a folder. How can I get this in C#?

The code below returns all the file names:

DirectoryInfo di = new DirectoryInfo(imgfolderPath);
foreach (FileInfo fi in di.GetFiles())
{
    if (fi.Name != "." && fi.Name != ".." && fi.Name != "Thumbs.db")
    {
        string fileName = fi.Name;
        string fullFileName = fileName.Substring(0, fileName.Length - 4);

         MessageBox.Show(fullFileName);
    }
}

I need the first file name.

Answer 1

There's a few ways you could do this:

• You could add a break statement after handling the first file. This will exit the foreach loop.

• DirectoryInfo.GetFiles returns an array so you can assign it to a variable and scan through the elements until you find a suitable element.

• Or if you are using .NET 3.5 you could look at the FirstOrDefault method with a predicate.

Here's some code:

string firstFileName =
    di.GetFiles()
      .Select(fi => fi.Name)
      .FirstOrDefault(name => name != "Thumbs.db");

Answer 2

If you are using .Net 4.0 you should do this instead...

var firstFileName = di.EnumerateFiles()
                      .Select(f => f.Name)
                      .FirstOrDefault();

... .GetFiles() creates an array and as such must scan all files. .EnumerateFiles() will return an IEnumerable<FileInfo> so it doesn't have to do as much work. You probably won't notice mush of a difference on a local hard drive with a small number of files. But a network share, thumb drive/memory card, or huge number of files would make this obvious.

Answer 3

FileInfo fi = di.GetFiles()[0];

Notes:

• The code throws an exception if there are no files.
• "First" is ambiguous — do you mean any file, or the first one alphabetically? In the latter case, you may need to worry about stuff like case-sensitivity and locale-dependent sorting.

Answer 4

using System.IO;
using System.Linq;

var firstFile = Path.GetFileName(Directory.GetFiles(@"c:\dir", "*.*")
    .FirstOrDefault(f => !String.Equals(
        Path.GetFileName(f),
        "Thumbs.db",
        StringComparison.InvariantCultureIgnoreCase)));

Answer 5

In reply to riad's comment to me:

In addition to abatischchev's solution:

var file = Directory.GetFiles(@"C:\TestFolder", "*.*")
            .FirstOrDefault(f => f != @"C:\TestFolder\Text1.txt");

I would add this to get the name only:

Console.WriteLine(file.Substring(file.LastIndexOf('\\')  + 1));

Which generates the output Text2.txt (I have three text tiles in that folder called Text1.txt, Text2.txt and text3.txt.