Question

What is the syntax for setting multiple file-extensions as searchPattern on Directory.GetFiles()? For example filtering out files with .aspx and .ascx extensions.

// TODO: Set the string 'searchPattern' to only get files with
// the extension '.aspx' and '.ascx'.
var filteredFiles = Directory.GetFiles(path, searchPattern);

Update: LINQ is not an option, it has to be a searchPattern passed into GetFiles, as specified in the question.

Answer 1

I believe there is no “out of the box” solution, that’s a limitation of the Directory.GetFiles method.

It’s fairly easy to write your own method though, here is an example.

The code could be:

/// <summary>
/// Returns file names from given folder that comply to given filters
/// </summary>
/// <param name="SourceFolder">Folder with files to retrieve</param>
/// <param name="Filter">Multiple file filters separated by | character</param>
/// <param name="searchOption">File.IO.SearchOption, 
/// could be AllDirectories or TopDirectoryOnly</param>
/// <returns>Array of FileInfo objects that presents collection of file names that 
/// meet given filter</returns>
public string[] getFiles(string SourceFolder, string Filter, 
 System.IO.SearchOption searchOption)
{
 // ArrayList will hold all file names
ArrayList alFiles = new ArrayList();

 // Create an array of filter string
 string[] MultipleFilters = Filter.Split('|');

 // for each filter find mathing file names
 foreach (string FileFilter in MultipleFilters)
 {
  // add found file names to array list
  alFiles.AddRange(Directory.GetFiles(SourceFolder, FileFilter, searchOption));
 }

 // returns string array of relevant file names
 return (string[])alFiles.ToArray(typeof(string));
}