How do I cut PDF pages?

Q: One of our clients provides us with PDF files in which each page
contains the Front and Back; we are currently using another software
to cut/split PDF pages but it is very slow when we get file with 3000+
pages and it does not work relaibly. Can I use PDFNet (http://
www.pdftron.com/pdfnet) to cut PDF pages?
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A: You can use the following code snippet as a starting point:

// C# sample to cut/split PDF pages (VB, JAVA, C/C++ is along the same
lines).

PDFDoc doc = new PDFDoc("my.pdf");
doc.InitSecurityHandler();

int pgnum = doc.GetPageCount();
for (int i = 1; i <= pgnum; ++i)
{
  // Clone the page
  PageIterator itr = doc.GetPageIterator(i * 2 - 1);
  Page pg = itr.Current();
  itr.Next();
  doc.PageInsert(itr, pg);

  // Adjust the crop box on the first page
  Rect box = pg.GetCropBox();
  box.x2 = (box.x1 + box.x2) / 2;
  pg.SetCropBox(box);

  // Adjust the crop box on the second page
  pg = doc.GetPage(i * 2);
  box = pg.GetCropBox();
  box.x1 = (box.x1 + box.x2) / 2;
  pg.SetCropBox(box);
}
doc.Save("out.pdf", 0);
doc.Close();

To download full sample code:
    http://groups.google.com/group/pdfnet-sdk/web/PDFPageCut.cs

A relevant sample in PDFNet SDK i RectTest sample: