TFile help again

ROOT
1

I am trying to write a couple of histograms to a file using a macro similar to the one below but it doesnt seem to work… the following error message appears -
Error in TFile::TFile: file name is not specified
Warning in TFile::Write: file not opened in write mode

but i thought i have already specified the file name??

void ATP1() {

char *m_output_ntuple;

TFile *m_f = m_output_ntuple;

m_f = new TFile(m_output_ntuple,“NEW”);

TF1 *Fcn4 = new TF1(“Fcn4”,func1,0,3,1);

Fcn4->SetNpx(1000);
Double_t x, y;
y=Fcn4->GetMaximum(0.5,1.0);
x=Fcn4->GetMaximumX(0.5,1.0);
cout<<x;
cout<<" ";
cout<<y;
Fcn4->SetLineWidth(2);
Fcn4->SetLineColor(kMagenta);

m_f->Write();

m_f->Close();

}

thanks for all your help

Maki

2

Hum!!! you are mixing types in a funny way. Instead of

char *m_output_ntuple; TFile *m_f = m_output_ntuple; m_f = new TFile(m_output_ntuple,"NEW"); do

const char *m_output_ntuple = "the file name"; TFile *m_f = new TFile(m_output_ntuple,"NEW");
Rene