Errors: Compiling

In general it is usually not too difficult to figure out what the compiler is complaining about as it points to the line at fault. Problems can be hard to understand if the error you have made has a knock-on effect. The following compilation problems are covered:-

Compiling rootcint dictionaries

If rootcint dictionaries (code generated by rootcint that contain dictionaries of user classes) fail to compile, check that:-

Missing member function definitions

Make sure you have included the class's header file rather than just an incomplete class definition i.e. you have e.g.:-
   #include "MyClass.h"
instead of just:-
   class MyClass;

Conflicting member function definitions

Definitions in the header and implementation files must be identical, and that includes any const keywards. For example:-
   Int_t GetInt() const;
does not match:-
   Int_t MyClass::GetInt() {return fInt;}
It has to be:-
   Int_t MyClass::GetInt() const {return fInt;}

Conflicting return types

One problem that catch the unwary is that if const member functions return pointers to themselves or internal components, then these pointers must also be const. Its logical really: const member functions are the only functions allowed to access objects in read-only memory, and of course any pointers into such objects must be read-only too.

Syntax errors involving < and >

If you get syntax errors and the code looks a bit like this:- > <<<<<<< <filename> > > ... > ======= > > ... > >>>>>>> 1.18 then this is a CVS conflict. CVS has found that it cannot merge a repository update into you local file system because a change made locally conflicts with an official change. This can happen if, for example, you accidentally modify local code. If you really didn't mean to make a local change then the simplest course of action is to delete the local code and restore from CVS:- cd <problem directory> rm <problem file> cvs update <problem file> If you did mean to make a change then the conflict has to be understood and resolved.

General errors

If you cannot see what is wrong:-

Contact: Nick West (>)