Get filenames without path of a specific directory

You can extract the filename from full path.

.NET 3, filenames only

var filenames3 = Directory
                .GetFiles(dirPath, "*", SearchOption.AllDirectories)
                .Select(f => Path.GetFileName(f));

.NET 4, filenames only

var filenames4 = Directory
                .EnumerateFiles(dirPath, "*", SearchOption.AllDirectories)
                .Select(Path.GetFileName); // <-- note you can shorten the lambda

Return filenames with relative path inside the directory

// - file1.txt
// - file2.txt
// - subfolder1/file3.txt
// - subfolder2/file4.txt

var skipDirectory = dirPath.Length;
// because we don't want it to be prefixed by a slash
// if dirPath like "C:\MyFolder", rather than "C:\MyFolder\"
if(!dirPath.EndsWith("" + Path.DirectorySeparatorChar)) skipDirectory++;

var filenames4s = Directory
                .EnumerateFiles(dirPath, "*", SearchOption.AllDirectories)
                .Select(f => f.Substring(skipDirectory));

confirm in LinqPad...

filenames3.SequenceEqual(filenames4).Dump(".NET 3 and 4 methods are the same?");

filenames3.Dump(".NET 3 Variant");
filenames4.Dump(".NET 4 Variant");
filenames4s.Dump(".NET 4, subfolders Variant");

Note that the *Files(dir, pattern, behavior) methods can be simplified to non-recursive *Files(dir) variants if subfolders aren't important

You can get the files name of particular directory using GetFiles() method of the DirectoryInfo class. Here are sample example to list out all file and it's details of particular directory

System.Text.StringBuilder objSB = new System.Text.StringBuilder();
    System.IO.DirectoryInfo directory = new System.IO.DirectoryInfo("d:\\");
    objSB.Append("<table>");
    objSB.Append("<tr><td>FileName</td>" + 
                 "<td>Last Access</td>" + 
                 "<td>Last Write</td>" + 
                 "<td>Attributes</td>" + 
                 "<td>Length(Byte)</td><td>Extension</td></tr>");

    foreach (System.IO.FileInfo objFile in directory.GetFiles("*.*"))
    {
        objSB.Append("<tr>");

        objSB.Append("<td>");
        objSB.Append(objFile.Name);
        objSB.Append("</td>");

        objSB.Append("<td>");
        objSB.Append(objFile.LastAccessTime);
        objSB.Append("</td>");

        objSB.Append("<td>");
        objSB.Append(objFile.LastWriteTime);
        objSB.Append("</td>");

        objSB.Append("<td>");
        objSB.Append(objFile.Attributes);
        objSB.Append("</td>");

        objSB.Append("<td>");
        objSB.Append(objFile.Length);
        objSB.Append("</td>");

        objSB.Append("<td>");
        objSB.Append(objFile.Extension);
        objSB.Append("</td>");

        objSB.Append("</tr>");
    }
    objSB.Append("</table>");

    Response.Write(objSB.ToString());

This example display list of file in HTML table structure.