how to get all file name in a folder and its subfolder

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C#

C#4.0

Hello,
how to get all file name in a folder and its subfolder in web .I am using this code but it cant read file name which is inside other folder in this folder
(e.g-D:\\Test\\Application\\common)

DataTable ord = new DataTable("Table");
        DataColumn c = new DataColumn();
        ord.Columns.Add(new DataColumn("Number", Type.GetType("System.Int32")));
        ord.Columns.Add(new DataColumn("Name", Type.GetType("System.String")));
        ord.Columns.Add(new DataColumn("Size", Type.GetType("System.String")));
        ord.Columns.Add(new DataColumn("CreationTime", Type.GetType("System.String")));
        ord.Columns.Add(new DataColumn("FolderName", Type.GetType("System.String")));

        string path = "D:\\Test\\Application";
        DirectoryInfo dir = new DirectoryInfo(path);
        foreach (FileInfo flInfo in dir.GetFiles())
        {
            count++;
            String name = flInfo.Name;
            long size = flInfo.Length;
            DateTime creationTime = flInfo.CreationTime;
            ord.Rows.Add(count, name, size, creationTime,"");
        }