CloneTreeCorruption.cc

//compile as c++ -g `root-config --cflags --libs` CloneTreeCorruption.cc -o CloneTreeCorruption
#include "TFile.h"
#include "TTree.h"

int main(int argc, const char** argv) {
    TFile* inf = new TFile("DoubleEG_Run2015D_v4_7_post.root");
    TTree* intree = (TTree*)(inf->Get("mt2"));  
    ULong64_t evt;
    intree->SetBranchAddress("evt", &evt);
    TFile* outf = new TFile("out.root", "RECREATE");
    TTree* outtree = intree->CloneTree(0);
    outtree->SetAutoSave(10);
    for (int i=0; i<intree->GetEntries(); i++) {
        intree->GetEntry(i);
        outtree->Fill();
    }
    return 0;
}