ROOT6 won't let me pass a histogram name as argument to a function

[OtaviusDecius]

Hi there,

My root file contains several histograms.
I open the root file in the main code with:

TFile *f = TFile::Open("t0RPrelui2015all.root");

I want to call a function plotall() which should plot
all the histograms as per:

plot1d(rp_x_124,"X (cm)","0.1cm","lin","lin")

This code compiles fine in ROOT5.
However, when I try to compile it with ROOT 6.16/00
it gives the error:

[lgemedia@zabriskie manyplots]$ root mycode.C
   ------------------------------------------------------------
  | Welcome to ROOT 6.16/00                  https://root.cern |
  |                               (c) 1995-2018, The ROOT Team |
  | Built for linuxx8664gcc on Jan 23 2019, 09:06:13           |
  | From tags/v6-16-00@v6-16-00                                |
  | Try '.help', '.demo', '.license', '.credits', '.quit'/'.q' |
   ------------------------------------------------------------

root [0] 
Processing mycode.C...
In file included from input_line_10:1:
/home/lgemedia/totem/manyplots/mycode.C:69:10: error: use of undeclared identifier 'rp_x_124'
  plot1d(rp_x_124,"X (cm)","0.1cm","lin","lin")
             ^
root [1] .q

I have read and tried many things unsuccessfully.

mycode.C
-------------
#include <TPad.h>
#include <TStyle.h>
#include <TPave.h>
#include <TPaletteAxis.h>
#include <TLatex.h>
#include "TCanvas.h"
//
#include "TSystem.h"
#include "TROOT.h"
#include "TFile.h"
#include "TTree.h"
#include <Riostream.h>
//
using namespace std;

void mycode()
{
  TFile *f = TFile::Open("t0RPrelui2015all.root");
  cout << "             in root:            " << endl;
  cout << "          .x makeplot.C          " << endl;
}

void plot1d(TH1F* string1, TString xtitle, TString binning, TString scaley1, TString scalex1)
{
  TCanvas * c1 = new TCanvas("c1","c1",1200,800);
  string1->Draw();
  string1->GetXaxis()->SetTitle(xtitle);
  string1->GetYaxis()->SetTitle("# of Events/" + binning);
  string1->GetXaxis()->CenterTitle();
  string1->GetYaxis()->CenterTitle();
  string1->GetXaxis()->SetTitleOffset(1.2);
  string1->GetYaxis()->SetTitleOffset(1.2);
  c1->Update();
  if (scalex1 == "log"){
    gPad->SetLogx();
    }
  if (scaley1 == "log"){
    gPad->SetLogy();
    }
  c1->Modified();
  TString hname1 = string1->GetName();
  c1->SaveAs(hname1 + ".png");
}

void plotall()
{
  //  
  //TString myplot="makeplot.C";
  //gROOT->Macro(myplot.Data());
  //
  //TH1* readThis = 0;
  //file->GetObject("hpx", readThis);
  //
  //TFile *f = TFile::Open("t0RPrelui2015all.root");
  //plot1d(f->GetObject("rp_y_125",readThis),"X (cm)","0.1cm","lin","lin");
  plot1d(rp_x_124,"X (cm)","0.1cm","lin","lin")
  plot1d(rp_x_125,"X (cm)","0.1cm","lin","lin")
  plot1d(rp_y_124,"X (cm)","0.1cm","lin","lin")
  plot1d(rp_y_125,"X (cm)","0.1cm","lin","lin")
  cout << " ...all set ! " << endl;
  //
}

Does anyone know what is wrong with this syntax?

Thanks in advance.
Luiz Emediato

---

_ROOT Version: 6.16/00
_Platform: Fedora 29
_Compiler: gcc (GCC) 8.3.1 20190223 (Red Hat 8.3.1-2)

---

[pcanal]

ROOT v6 uses Cling instead of CINT and Cling is much more strict about C++ syntax and the shortcut this code relied upon is no longer supported. You need to use:

  TH1F *rp_x_124; gFile->GetObject("rp_x_124", rp_x_124);
  TH1F *rp_x_125; gFile->GetObject("rp_x_125", rp_x_125);
  TH1F *rp_y_124; gFile->GetObject("rp_y_124", rp_y_124);
  TH1F *rp_y_125; gFile->GetObject("rp_y_125", rp_y_125);
  plot1d(rp_x_124,"X (cm)","0.1cm","lin","lin")
  plot1d(rp_x_125,"X (cm)","0.1cm","lin","lin")
  plot1d(rp_y_124,"X (cm)","0.1cm","lin","lin")
  plot1d(rp_y_125,"X (cm)","0.1cm","lin","lin")

Cheers,
Philippe.

[OtaviusDecius]

Thanks a lot, Philippe.

cheers,
Luiz