Can't Fill TH2F after I split my code in multiple files

ROOT
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1

Hello everyone,

I’m an italian student and I’ve been working on a lot of data for my thesis in physics, using ROOT to plot histograms and graphs: I’ll get to the point straight ahead.

My source code, a single .cpp file, looked kind of like this:

#include < all the libraries i need >
< declaration of the various functions, with all the instructions > 
int main ()
{
     TH1F h1 = ( ... );
     TH2F h2 = (  "", "", nBins, -range1, range1, nBins, -range2, range2 );
     // fill histograms here
     while ( things happen )
     {
          h1.Fill( v[i] );
          h2.Fill( v[i], w[i] );
          i++;
     }
     < print histograms here >;
     return 0;
}

Everything was fine, and I could correctly plot the scatterplot I needed to show a correlation between two variables. Here’s a draft.

q1e-1_scat
q1e-1_scat1916×1052 25.6 KB

Having made lots of custom functions for data analysis, I have decided to split my code into three different parts:
1- header file: functions.h -> names of the functions and all c++ and ROOT libraries are declared here.
2- functions.cpp: what the various functions do appears here + #include “functions.h” on top
3- main.cpp: no need to explain this, nothing changed here + #include “functions.h” on top
The code is compiled correctly.

Now, my source code looks quite like this:

#include "functions.h"

int main ()     // nothing changed here
{
      TH1F h1 = ( ... );
      TH2F h2 = (  "", "", nBins, -range1, range1, nBins, -range2, range2 );
     // fill histograms here
     while ( things happen )
     {
          h1.Fill( v[i] );
          h2.Fill( v[i], w[i] );
          i++;
     }
     < print histograms here >;
     return 0;
}

And now, apparently for no reason at all, h2 is printed empty. The axis range is plotted correctly, I just don’t understand why on earth h2 pleases me with all this emptiness. h1 is always printed correctly, by the way. Both libraries ( “TH1F.h” and “TH2F.h” ) are included in the same file ( functions.h ), and no errors appear when I compile my code.

Fun part in this absurdity: if, for example, I “tell” h2 to fill the bin corresponding to the coordinates (0., 0.) ten thousand times, the histogram is printed correctly, with te thousand entries in ( 0., 0. ) - If I manually edit range1 and range2 ( see picture ) and fill the histogram with my actual data, h2 is either printed empty or in a completely wrong way. ( New users can only post one image in a post, sorry >__> )

Does anyone know why this is happening? I really don’t know what to do to fix this issue and I could use some help >__>

( Of course I can just merge my files and ignore the issue, but my code was just too messy to deal with and I wouldn’t want to do that. Free bug report, I guess? :slight_smile: )

Thank you for your help,
Freddy

ROOT Version: 6.18.04
Platform: Ubuntu 18.04 on Windows for Developers ( + Xming )
Compiler: No idea, I have been taught to type " c++ -o program main.cpp ‘root-config --cflags --glibs’ " in my terminal and it works

2

Can you provide a small reproducer ?

3

I’m sorry, what do you mean with reproducer?

4

A piece of code we can run reproducing your problem.

5

Yes! Uploading now. This should work. I got rid of all the unnecessary parts to make it simple.

reproducer.cpp (1.1 KB)

functions.h (2.1 KB)

6

You need to read this file. I can’t upload more than two files per post :frowning:

data.txt (206.1 KB)

7

print.cpp is missing

8

print.cpp (1.0 KB)

Here it is, sorry.

9

there is some undeclared variables in your program:

/Users/couet/Downloads/reproducer.cpp:36:14: error: use of undeclared identifier 'angvar'
                scat.Fill( angvar[n] , eccvar[n] );     // this does not work: either blank or messed up (line 28 )
                           ^
/Users/couet/Downloads/reproducer.cpp:36:26: error: use of undeclared identifier 'eccvar'
                scat.Fill( angvar[n] , eccvar[n] );     // this does not work: either blank or messed up (line 28 )
                                       ^
/Users/couet/Downloads/reproducer.cpp:38:13: error: use of undeclared identifier 'angvar'
                if ( n == angvar.size() || n == eccvar.size() ) break;
                          ^
/Users/couet/Downloads/reproducer.cpp:38:35: error: use of undeclared identifier 'eccvar'
                if ( n == angvar.size() || n == eccvar.size() ) break;
10

reproducer.cpp (1.0 KB)

Corrections have been made. angvar is the X vector, eccvar is the Y vector. I forgot to rename and edit that part, I’m sorry. Grab the edited file down here, there was an extra dot causing problems.

11

I would say you need a Application as in the modified files:
functions.h (2.1 KB) reproducer.cpp (1.1 KB)

That works for me

Note also your program produces warnings:

reproducer.cpp:41:10: warning: comparison of integers of different signs: 'int' and 'std::__1::vector<double, std::__1::allocator<double> >::size_type' (aka 'unsigned long') [-Wsign-compare]
                if ( n == X.size() || n == Y.size() ) break;
                     ~ ^  ~~~~~~~~
reproducer.cpp:41:27: warning: comparison of integers of different signs: 'int' and 'std::__1::vector<double, std::__1::allocator<double> >::size_type' (aka 'unsigned long') [-Wsign-compare]
                if ( n == X.size() || n == Y.size() ) break;
                                      ~ ^  ~~~~~~~~
2 warnings generated.
12

I receive this error message now, once the program gets to the printing part ( my folder is empty now, no images are present ):

Error in <TASImage::WriteImage>: no image loaded
13

The files I sent you are working for me. How do you compile/run the program ?

14

I write this: c++ -o myExe myExe.cpp ’ root-config --cflags --glibs ’
Then i just type ./myExe
( The apostrophe is actually a ` )

Edit, late at night: I have finally found the mistake I made while splitting the code into different files.

Basically, it was not a ROOT problem with the class but a problem of variables in the group of files. I will provide further explanation if needed, but I finally understood why it was compiled correctly but gave the wrong result. Still, thank you very much for your help.

15

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