Why not use the PostedFiles property? You might need to rewrite the "if (i < 5)...", not clear what you trying to do there.
Updated solution to target Framework 4.0
if (flpProspectus.HasFile || flpOrientation.HasFile)
{
string fileExtension = string.Empty;
int fileSize = 0;
HttpFileCollection hfc = Request.Files;
string[] arr = new string[5];
string path1, path2, path3, path4, path5 = string.Empty;
string filePath = string.Empty;
for (int i = 0; i < hfc.Count; i++)
{
if (hfc.GetKey(i) == "flpOrientation")
{
filePath = "college/fileupload3";
}
if (hfc.GetKey(i) == "flpProspectus")
{
filePath = "college/fileupload4";
}
fileExtension = System.IO.Path.GetExtension(hfc[i].FileName);
fileSize = hfc[i].ContentLength;
if (hfc[i].ContentLength > 0)
{
hfc[i].SaveAs(Server.MapPath(string.Format("~/{0}/", filePath)) + System.IO.Path.GetFileName(hfc[i].FileName));
string filepath = Server.MapPath(string.Format("~/{0}/", filePath));
string path = string.Format("{0}/", filePath) + hfc[i].FileName;
if (i < 5)
{
arr[i] = path;
path1 = arr[0]; path2 = arr[1]; path3 = arr[2]; path4 = arr[3]; path5 = arr[4];
}
}
}
}