How to search for a SINGLE file in c#

Question

I want to search a directory and its subdirectories for a single file.

The directory tree is very large and i don't want to search all the directory tree , but just search to the first found file.

Currently I have tried the following:

IEnumerable<string> files = Directory.EnumerateFiles(
Directory.GetCurrentDirectory(),
"myFile.ext",
SearchOption.AllDirectories);

myFileInfo = new FileInfo(files.First());

the problem with the code above is that it search all the directory tree.

my main focus in finding the file is performance.

You may have to write your own iterator of directories using DirectoryInfo and not search with the AllDirectories option to get the option you are looking for. — Martin Noreke, Oct 27 '15 at 09:55
What's wrong with this: https://msdn.microsoft.com/en-us/library/ms143316.aspx ? — Nasreddine, Oct 27 '15 at 09:58
Did you measure actual performance of EnumerateFiles before searching for better solution? — Andrey, Oct 27 '15 at 10:05
What are you trying to do? Your code will *not* traverse all files - it *is* an enumerator which means you can get the first result before the entire tree gets traversed. Actually, if you used [DirectoryInfo.EnumerateFiles](https://msdn.microsoft.com/en-us/library/dd413343(v=vs.110).aspx) you'd get back a FileInfo directly, no need to get the path first, then create a FileInfo — Panagiotis Kanavos, Oct 27 '15 at 10:06
This is the fastest method you could find, see [here](http://stackoverflow.com/a/5669635/1155650) for difference. — Rohit Vipin Mathews, Oct 27 '15 at 10:11

Alb · Answer 1 · 2020-01-20T15:39:35.723

What you have tried is indeed the solution. It does not loop through all your directory tree but a part of it; until the file is found.

Alternatively - as commented -, you can get FileInfo class directly (if necessary):

FileInfo fileInfo = new DirectoryInfo(Directory.GetCurrentDirectory())
                            .EnumerateFiles("myFile.ext", SearchOption.AllDirectories)
                            .FirstOrDefault();

score 0 · Answer 2 · answered Oct 27 '15 at 10:15

String searchFile(String searchPath, String fileName)
{
    DirectoryInfo dir = new DirectoryInfo(searchPath);
    DirectoryInfo[] dirs = dir.GetDirectories();

    FileInfo[] files = dir.GetFiles();
    foreach (FileInfo file in files)
    {
        if (file.Name.Equals(fileName))
            return searchPath;
    }

    foreach (DirectoryInfo subDir in dirs)
    {
        String value = searchFile(Path.Combine(searchPath, subDir.Name), fileName);
        if (value != null)
            return value;
    }
    return null;
}

private void Form1_Load(object sender, EventArgs e)
{
    String searchPath = @"C:\PathHere";
    String searchFile = "log.txt";

    String foundFileAt = this.searchFile(searchPath, searchFile);
}

score 0 · Answer 3 · answered Oct 27 '15 at 10:18

How about this:

public string FindFirstFile(string dir, string file)
{
    if (System.IO.File.Exists(Path.Combine(dir, file)))
    {
        return Path.Combine(dir, file);
    }
    foreach (var subDir in System.IO.Directory.EnumerateDirectories(dir))
    {
        var result = FindFirstFile(subDir, file);
        if (result != null)
        {
            return result;
        }
    }
    return null;
}

Usage:

var topDirectory = @"D:\top directory";
var file = "foo.txt";
var theFile = FindFirstFile(topDirectory, file);

It's more complex than the build in functionality, but you get more control over when when you return.

How to search for a SINGLE file in c#

3 Answers3