Collections2

// collections2 -- C++ port of examples\Vb6\collections2\collections2.bas
// Like collections, but adds sortable collection fields and per-item field
// values, then validates the collection.
#include <lumaspdf.h>
#include "repo_root.h"
#include <cstdio>
#include <string>

static std::string exeDir(const char* a0){ std::string s(a0); auto p=s.find_last_of("\\/"); return p==std::string::npos?".":s.substr(0,p); }

static const char* TF = LUMAS_REPO_ROOT "/";

static SI32 PDF_CALL ErrProc(void* Data, SI32 ErrCode, const char* ErrMessage, SI32 ErrType){
    if(ErrMessage) printf("%s\n", ErrMessage);
    return 0;   // We try to continue if an error occurs
}

int main(int argc, char** argv){
    PPDF pdf = pdfNewPDF();
    pdfCreateNewPDFA(pdf, "");            // The output file is opened later
    pdfSetOnErrorProc(pdf, nullptr, ErrProc);

    pdfSetImportFlags(pdf, ifImportAll | ifImportAsPage);
    std::string cover = std::string(TF) + "collection_en.pdf";
    if(pdfOpenImportFileA(pdf, cover.c_str(), ptOpen, "") < 0){
        pdfDeletePDF(pdf);
        printf("Input file \"%s\" not found!\n", cover.c_str());
        return 0;
    }
    pdfImportPDFFile(pdf, 1, 1.0, 1.0);
    pdfCloseImportFile(pdf);
    pdfCreateCollection(pdf, civTile);

    // Add a user defined field Index so that we can sort in any order we want.
    SI32 ef = pdfCreateCollectionFieldA(pdf, cisCustomNumber, 0, "File index", "Index", 0, 1);
    pdfSetColSortField(pdf, ef, 1);

    pdfCreateCollectionFieldA(pdf, cisFileName, 1, "File name", "", 1, 1);
    pdfCreateCollectionFieldA(pdf, cisSize, 2, "File size", "", 1, 0);
    pdfCreateCollectionFieldA(pdf, cisModDate, 3, "Modification date", "", 1, 0);

    std::string taxform = std::string(TF) + "sample_form.pdf";
    std::string emf     = std::string(TF) + "sample_vector.emf";
    std::string txt     = std::string(TF) + "sample.txt";

    ef = pdfAttachFileA(pdf, taxform.c_str(), "A PDF file...", 1);
    pdfSetColDefFile(pdf, ef);
    pdfCreateColItemNumber(pdf, ef, "Index", 0.0, "");

    ef = pdfAttachFileA(pdf, emf.c_str(), "An EMF file...", 1);
    pdfCreateColItemNumber(pdf, ef, "Index", 1.0, "");

    ef = pdfAttachFileA(pdf, txt.c_str(), "A text file...", 1);
    pdfCreateColItemNumber(pdf, ef, "Index", 2.0, "");

    // Let's check whether the collection is valid.
    pdfCheckCollection(pdf);

    std::string outFile;
    if(pdfHaveOpenDoc(pdf) != 0){
        outFile = exeDir(argv[0]) + "/out.pdf";
        if(pdfOpenOutputFileA(pdf, outFile.c_str()) == 0){
            pdfDeletePDF(pdf);
            return 0;
        }
    }
    pdfCloseFile(pdf);
    printf("PDF Collection \"%s\" successfully created!\n", outFile.c_str());
    pdfDeletePDF(pdf);
    return 0;
}

This file is in the SDK at examples/cpp_linux/collections2/collections2.cpp. The build fails if this page and that file ever differ.