Directory.GetFiles in .Net 3.5 and Directory.EnumerateFiles in .Net 4.0 neither supports multiple patterns when searching for files. The reason is that it uses FindFirstFile / FindNextFile of kernel32.dll which lacks the support.
Initial thought would be to create an extension method to the Directory class, but since it’s a static class that’s not possible. The second best choice is to create a short helper class instead. What we do is do a wildcard search with “*” and filter the results with a regular expression.
If you return a large result set the new Enumerable version in .Net 4.0 is preferable as it returns values to act on as you go along.
public static class MyDirectory
{
// Works in .Net 3.5 - you might want to create several overloads
public static string[] GetFiles(string path, string searchPatternExpression, SearchOption searchOption)
{
if (searchPatternExpression == null) searchPatternExpression = string.Empty;
Regex reSearchPattern = new Regex(searchPatternExpression);
return Directory.GetFiles(path, "*", searchOption).Where(file => reSearchPattern.IsMatch(Path.GetFileName(file))).ToArray();
}
// Works in .Net 4.0 - inferred overloads with default values
public static IEnumerable<string> GetFiles(string path, string searchPatternExpression = "", SearchOption searchOption = SearchOption.TopDirectoryOnly)
{
Regex reSearchPattern = new Regex(searchPatternExpression);
return Directory.EnumerateFiles(path, "*", searchOption).Where(file => reSearchPattern.IsMatch(Path.GetFileName(file)));
}
// Works in .Net 4.0 - takes same patterns as old method, and executes in parallel
public static IEnumerable<string> GetFiles(string path, string[] searchPatterns, SearchOption searchOption = SearchOption.TopDirectoryOnly)
{
return searchPatterns.AsParallel().SelectMany(searchPattern => Directory.EnumerateFiles(path, searchPattern, searchOption));
}
}
