C#

public class A : C
{
}

public class B : C
{
}

public interface C
{
    // Common implementation here.
}

// c:\MyDir\ is your parent Directory .... 
string[] filePaths = Directory.GetFiles(@"c:\MyDir\", "*.gif",
                                         SearchOption.AllDirectories);

Stark DaFixzer wrote:

SearchOption.AllDirectories

Luc Pattyn wrote:

Yes it works.There are some disadvantages: it will search all before it returns anything.

michaelgr1 wrote:

How can i do it?

using System.IO;

string FindFile(string initDirectory, string fileToFind)
{
  DirectoryInfo dir = new DirectoryInfo(initDirectory);
  foreach(FileInfo file in dir.GetFiles())
  {
    if(file.Name == fileToFind)
       return file.FullName;
  }
  foreach(DirectoryInfo subDir in dir.GetDirectories())
  {
    return FindFile(subDir.FullName, fileToFind);
  }
  return null;
}