filename = GetFileName();
if (filename == "filename1.csv") {
  path = "C:\\Dir1\\" + filename;
} else if (filename == "filename2.csv") {
  path = "C:\\Dir2\\" + filename;
} else {
  path = "C:\\Dir3\\" + filename;
}
SaveAs(path);
MessageBox(path + " に保存しました。");