#includeIn this example, we first open a ROOT file containing a histogram with the name "histogram". We then retrieve the histogram from the file using the Get function, and store it as a TH1D pointer. Finally, we use the GetEntries function to obtain the number of entries in the histogram, and print it to the console. The package library used in this example is ROOT, as indicated by the inclusion of the TH1D.h and TFile.h headers.#include #include void example() { TFile* file = TFile::Open("example.root", "READ"); TH1D* histogram = (TH1D*)file->Get("histogram"); // Get the number of entries in the histogram int num_entries = histogram->GetEntries(); std::cout << "Histogram has " << num_entries << " entries" << std::endl; file->Close(); }