This code will loop all the files inside the all subfolders of Shared Documents library in SharePoint 2010.
public ArrayList getfilesinfoder()
{
ArrayList al1 = new ArrayList();
string[] arr = LoopAllFolder();
SPSite site = SPContext.Current.Site;
for (int i = 0; i < arr.Length; i++)
{
SPFolder cols = site.OpenWeb().GetFolder("site.Url"+/Shared%20Documents/" + arr[i].ToString());
SPFileCollection files = cols.Files;
foreach (SPFile file in files)
{
al1.Add(file.Name.ToString());
}
}
return al1;
}