{

// Inheriting from MSDataWritingConsumer allows to change the data before

// they are written to disk (to "filename") using the processSpectrum_ and

// processChromatogram_ functions.

double TIC {};

int nr_spectra {};

// Create new consumer

TICWritingConsumer(const String& filename) : MSDataWritingConsumer(filename)

{}

// Add a data processing step for spectra before they are written to disk

void processSpectrum_(MSDataWritingConsumer::SpectrumType & s) override

{

for (const auto& p : s) TIC += p.getIntensity();

nr_spectra++;

}

// Empty chromatogram data processing

void processChromatogram_(MSDataWritingConsumer::ChromatogramType& /* c */) override {}

{

auto file_mzXML = OPENMS_DOC_PATH + String("/code_examples/data/Tutorial_FileIO_indexed.mzML");

// Create the consumer, set output file name, transform

TICWritingConsumer consumer("Tutorial_FileIO_output.mzML");

MzMLFile().transform(file_mzXML, &consumer);

std::cout << "There are " << consumer.nr_spectra << " spectra in the input file.\n";

std::cout << "The total ion current is " << consumer.TIC << std::endl;