pdfGetDocumentFileName

Returns the output path passed to pdfCreateNewPDF…/pdfOpenOutputFile (empty for in-memory output), as an instance-owned string; NULL on an invalid handle.

const char*    __stdcall pdfGetDocumentFileNameA(PPDF IPDF); /* bare = ANSI */
const wchar_t* __stdcall pdfGetDocumentFileNameW(PPDF IPDF);

C# (P/Invoke)

public static extern IntPtr pdfGetDocumentFileNameW(IntPtr IPDF);
public static extern IntPtr pdfGetDocumentFileName(IntPtr IPDF);
public static extern IntPtr pdfGetDocumentFileNameA(IntPtr IPDF);