Errors: Running

No symbol cout in current scope

This problem has made it into RootTalk on more than one occasion! It can happen if you have not loaded iostream.h, see First Steps: Typing in C++. Doing:- { #include <iostream.h> gROOT->Reset(); ...etc... } doesn't work as the Reset() clears the stack and looses the the definitions in the header. Doing:- { gROOT -> Reset(); #include <iostream.h> ...etc... } isn't much better. It works the first time but gives the error:- Warning: File "iostream.h" already loaded after that even though the definitions get wiped. Far better to put:- { G__loadfile("iostream.h"); } in rootlogon.C.

Can't call Class::MemberFunction() in current scope

Check the following:-

Error: class,struct,union or type ... not defined

This can be produced if the libraries listed on the link line are not in the right order. The linker may be smart enough to find all the symbols it needs but ROOT may not. ROOT, when building class definition data during execution, loads dictionary data in strict reverse order to the way the libraries appear on the load line. That way lower level class information is available to the system when building class definitions that depend on them. Getting the order wrong may mean that the system fails to find a class definition and prints an error.

Undefined symbol

With shared libraries, sections of the executable are not loaded until required. Normally any potential unresolved symbol is identified at load time but in exceptional cases, for example virtual destructors to abstract classes, errors can occur during execution. To resolve see Unresolved Global Symbols in Shared Libraries.

Failure in malloc/new

A failure in malloc while trying to allocate memory strongly suggest a memory leak. Here are a few common mistakes that can lead to leaks:-

Using delete instead of delete [] for an array

A common source of memory leaks is deleting only the first element of an array allocated on the heap. The incorrect code looks like:
    Type* ptr = new Type [nelements];
    delete ptr;
When instead the second of those lines should be:
    delete [] ptr;

Stack pointer going out of scope

Using a local i.e. stack pointer when creating a heap object can lead to trouble. Consider this code snippet:-
      MyClass* myObj = new MyClass(...);
At the end of the code block the local pointer myObj goes out of scope and is deleted. Unless the object it pointed to has already been deleted or has been pointed to by another pointer that survives, the memory allocated to the object is lost.

Re-initialization enforced macro G__CINTVERSION FILE: LINE:0

This usually means that you need to regenerate some dictionary file. To remake all these files in a test release:-
  \rm `find tmp -name "*Cint.*"`
  gmake all
If really necessary all the dictionaries in a Base Release can be regenerate in a similar way.
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Contact: Nick West (>)