Taking the address of a convenience variable value

Bob Rossi bob@brasko.net
Wed May 26 00:00:00 GMT 2004


On Tue, May 25, 2004 at 12:55:46PM -0400, Paul Dubuc wrote:
> In the June 2004 issue of the C/C++ User's Journal (p. 24) there is an 
> article on how to write user-defined commands for gdb to examine the 
> contents of STL vectors, sets and maps.  It looks extremely useful, so I 
> decided to try it modifying the commands for use with the GCC STL, but I 
> can't get some of the commands for sets and maps to work.  It relies on a 
> tecnique that involves being able to take the address of a convenience 
> variable value, for example:
> 
>   set $maptype = &$arg0._M_t._M_header->_M_value_field
>   set $maptypep = &$maptype
> 
> When I try this the 2nd statement gives me the error message
> 
>   Attempt to take address of value not located in memory.
> 
> It doesn't work with gdb 5.3 or 6.1 on Solaris.  The author claims that it 
> works on HP-UX, but I don't know why it would be any different.
> 
> Is there a way around this?  Or is there another source of user-defined 
> commands that can be used to print the contents of STL containers in gdb?  
> Any help would be very much appreciated.

I read that article and was wondering if it was necessary to compile the
STL with -g and not with -O2. I don't think the author mentioned it, but
how else could all of the symbols in the STL work properly with GDB?

Bob Rossi



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