extern long acdbSetDbmod(AcDbDatabase* pDb, long newVal); // 添加acdbSetDbmod的引用
extern "C"
AcApDocumentIterator* pDociterator;
AcApDocument* pDoc;
pDociterator = acDocManager->newAcApDocumentIterator();
for (; !pDociterator->done(); pDociterator->step())
{
pDoc = pDociterator->document();
acdbSetDbmod(pDoc->database(),0); // 就是這句代碼起了決定性作用
acDocManager->closeDocument(pDoc);
}