Re: gdb and iterators

[Maurizio Loreti]

glen_stark <stark@ifh.ee.ethz.ch> writes:

> Hi.
> 
> I hope I'm posting in the correct forum.  I'm debugging some code
> using iterators, and having trouble getting info on where the iterator
> is pointing to, and what.
> 
> i get:
> 
> 1: spli = (t_shapePtrListIter &) @0x226b00: {<_List_iterator_base> = {
>      _M_node = 0xa042980}, <No data fields>}
> 
> When I type "print spli"
> 
> and
> Attempt to take contents of a non-pointer value.
> 
> for "print *spli".  spli should be an list iterator pointing to
> pointer to a Shape (my own class).  Can someone tell me what's going
> on?

Simple.  Iterators are not pointers; they *may* be implemented as
pointers, but they are not required to be pointers.

>      is there a trick to getting iterator info?

This is the tricky part :-)  I do not use gdb, but I am surprised that
gdb could not understand how to interpret *spli , since an operator *
must be defined for iterators.  Maybe *(spli._M_node)?  I am afraid
you should explore how an iterator is defined by your compiler :-(

-- 
Maurizio Loreti                         http://www.pd.infn.it/~loreti/mlo.html
Dept. of Physics, Univ. of Padova, Italy              ROT13: ybergv@cq.vasa.vg