Error on loading shared library

Newbie
1

I’m new to root and C++ and Linux…
I have a MyClass.h and a MyClass.C file.
If I try to type

.x /Users/burial/Applications/root_v6.18.04/MyClass.C

I can successfully define

MyClass* t = new MyClass()

But when I try to run a .C file as shown:

#include "/Users/burial/Applications/root_v6.18.04/MyClass.h"

//.x /Users/burial/Applications/root_v6.18.04/MyClass.C

int main()
{
	MyClass* t = new MyClass();
	TTree *tgood = new TTree("tgood","");
	double pt;
	tgood->Branch("pt", &pt, "pt/D");
	int nTracks = t->Event_multi;
	t->GetEntry(1);
	nTracks = t->Event_multi;

	for(int i=0; i<nTracks; i++) {

			double px = t->Px[i];
			double py = t->Py[i];
			double pz = t->Pz[i];
			TVector3 mom(px,py,pz);
			pt = mom.Perp();

			tgood->Fill();
		}

		TFile f("/Users/burial/Desktop/test.root", "recreate");
		tgood->Write();
		f.Close();
                return 0;

}

It couldn’t work and shows like:

root [2] .x /Users/burial/Desktop/test.cpp
IncrementalExecutor::executeFunction: symbol '_ZN8TVector3C1Eddd' unresolved while linking [cling interface function]!
You are probably missing the definition of TVector3::TVector3(double, double, double)
Maybe you need to load the corresponding shared library?
IncrementalExecutor::executeFunction: symbol '_ZN7MyClassC1EP5TTree' unresolved while linking [cling interface function]!
You are probably missing the definition of MyClass::MyClass(TTree*)
Maybe you need to load the corresponding shared library?

I don’t know how to load the corresponding shared library. I tried the following command and it didn’t work:

.x  /Users/burial/Applications/root_v6.18.04/MyClass.h++
ROOT_prompt_3:1:1: error: expected expression
/Users/burial/Applications/root_v6.18.04/MyClass.h++
^
ROOT_prompt_3:1:2: error: use of undeclared identifier 'Users'
/Users/burial/Applications/root_v6.18.04/MyClass.h++
 ^
ROOT_prompt_3:1:8: error: use of undeclared identifier 'burial'
/Users/burial/Applications/root_v6.18.04/MyClass.h++
       ^
ROOT_prompt_3:1:15: error: use of undeclared identifier 'Applications'
/Users/burial/Applications/root_v6.18.04/MyClass.h++
              ^
ROOT_prompt_3:1:28: error: use of undeclared identifier 'root_v6'
/Users/burial/Applications/root_v6.18.04/MyClass.h++

What can I do to load the Corresponding shared library?

And there’s two other little questions, when I write a .C file and try to run it in root, should I put it in the same directory where root is? And I just tried type “echo $ROOTSYS”, it just shows blank, but I can still access the tutorials by “cd $ROOTSYS/tutorials” what’s wrong with this?

Thank you in advance.
(English is not my native language, if there’s some grammar mistakes please forgive them.;))

_ROOT Version:6.18/04
_Platform:Mac OSX Catalina 10.15.2
_Compiler:Mac OSX Terminal

2

gSystem->Load("libPhysics"); // TVector3

3

Where should I add this line, does it need to be included in the main function?

4

You need to execute it before you try to call your macro (on the ROOT prompt).

5

Do I need to put the .C file(my macro) in the …/root/macro folder too? Or this doesn’t matter?