是什么

string[] filesPNG = Directory.GetFiles(path, "*.png");
string[] filesJPG = Directory.GetFiles(path, "*.jpg");
string[] filesJPEG = Directory.GetFiles(path, "*.jpeg");

int totalArraySizeAll = filesPNG.Length + filesJPG.Length + filesJPEG.Length;
List<string> filesAll = new List<string>(totalArraySizeAll);
filesAll.AddRange(filesPNG);
filesAll.AddRange(filesJPG);
filesAll.AddRange(filesJPEG);

我不知道哪种解决方案更好，但我用这个:

String[] ext = "*.ext1|*.ext2".Split('|');

            List<String> files = new List<String>();
            foreach (String tmp in ext)
            {
                files.AddRange(Directory.GetFiles(dir, tmp, SearchOption.AllDirectories));
            }

Using GetFiles search pattern for filtering the extension is not safe!! For instance you have two file Test1.xls and Test2.xlsx and you want to filter out xls file using search pattern *.xls, but GetFiles return both Test1.xls and Test2.xlsx I was not aware of this and got error in production environment when some temporary files suddenly was handled as right files. Search pattern was *.txt and temp files was named *.txt20181028_100753898 So search pattern can not be trusted, you have to add extra check on filenames as well.

for

var exts = new[] { "mp3", "jpg" };

你可以:

public IEnumerable<string> FilterFiles(string path, params string[] exts) {
    return
        Directory
        .EnumerateFiles(path, "*.*")
        .Where(file => exts.Any(x => file.EndsWith(x, StringComparison.OrdinalIgnoreCase)));
}

不要忘记新的。net 4目录。EnumerateFiles用于性能提升(目录和文件的区别是什么?EnumerateFiles vs Directory.GetFiles?) “IgnoreCase”应该比“ToLower”(。EndsWith("aspx"， stringcompare . ordinalignorecase)而不是。tolower ().EndsWith("aspx"))

但EnumerateFiles的真正好处体现在你拆分过滤器并合并结果时:

public IEnumerable<string> FilterFiles(string path, params string[] exts) {
    return 
        exts.Select(x => "*." + x) // turn into globs
        .SelectMany(x => 
            Directory.EnumerateFiles(path, x)
            );
}

如果你不需要将它们转换为glob(即exts = new[] {"*.mp3"， "*.jpg"})，它会变得更快一些。

基于以下LinqPad测试的性能评估(注意:Perf只是重复委托10000次) https://gist.github.com/zaus/7454021

(从'duplicate'重新发布和扩展，因为这个问题特别要求没有LINQ:多个文件扩展searchPattern for System.IO.Directory.GetFiles)

我不能使用. where方法，因为我在. net Framework 2.0中编程(Linq只在. net Framework 3.5+中被支持)。

下面的代码不区分大小写(因此.cab或.cab也会被列出)。

string[] ext = new string[2] { "*.CAB", "*.MSU" };

foreach (string found in ext)
{
    string[] extracted = Directory.GetFiles("C:\\test", found, System.IO.SearchOption.AllDirectories);

    foreach (string file in extracted)
    {
        Console.WriteLine(file);
    }
}

List<string> FileList = new List<string>();
DirectoryInfo di = new DirectoryInfo("C:\\DirName");

IEnumerable<FileInfo> fileList = di.GetFiles("*.*");

//Create the query
IEnumerable<FileInfo> fileQuery = from file in fileList
                                  where (file.Extension.ToLower() == ".jpg" || file.Extension.ToLower() == ".png")
                                  orderby file.LastWriteTime
                                  select file;

foreach (System.IO.FileInfo fi in fileQuery)
{
    fi.Attributes = FileAttributes.Normal;
    FileList.Add(fi.FullName);
}