STL Support Tools

When you try to use GDB's "print" command to display the contents of a vector, a stack, or any other GDB abstract data structure, you will get useless results. Instead, download and install one of following tools to properly view the contents of STL containers from within GDB.

• GDB 7.0 will include support for writing pretty-printers in Python. This feature, combined with the pretty-printers in the libstdc++ svn repository, yields the best way to visualize C++ containers. Some distros (Fedora 11+) ship all this code in a way that requires no configuration; in other cases,this email message explains how to set everything up. The main points have been redacted here:

  1. Check-out the latest Python libstdc++ printers to a place on your machine. In a local directory, do:

     • svn co svn://gcc.gnu.org/svn/gcc/trunk/libstdc++-v3/python

  2. Add the following to your ~/.gdbinit. The path needs to match where the python module above was checked-out. So if checked out to: /home/maude/gdb_printers/, the path would be as written in the example:

     • pythonimport syssys.path.insert(0, '/home/maude/gdb_printers/python')from libstdcxx.v6.printers import register_libstdcxx_printersregister_libstdcxx_printers (None)end

  The path should be the only element that needs to be adjusted in the example above. Once loaded, STL classes that the printers support should printed in a more human-readable format. To print the classes in the old style, use the/r (raw) switch in the print command (i.e., print /r foo). This will print the classes as if the Python pretty-printers were not loaded.

• gdb-stl-views is a set of GDB macros that can display the contents of many STL containers: list, vector, map, multimap, set, multiset, dequeue, stack, queue, priority_queue, bitset, string, and widestring. Writen and currently maintained by Dan Marinescu - PhD. The author formally disclaims copyright to this source code. In place of a legal notice, here is a blessing: May you do good and not evil. May you find forgiveness for yourself and forgive others. May you share freely, never taking more than you give!

  • You can download it here or here

  • Tutorials and an alternative download are hosted at yolinux.com.

• gdb++ is a Perl script which extends gdb. It comes bundled as part of the Devel::GDB::Reflect Perl module. Firstuse CPAN to install the module, then follow the gdb++ usage instructions. Developed by Stanford PhD student Antal Novak.

• There are other options. Tom Malnar wrote a set of GDB macros similar to Dan's (http://thread.gmane.org/gmane.comp.gcc.g++.general/4060/focus=4167 ) but it doesn't cover as wide a variety of containers. Gilad Mishne wrote a different set of macros (http://www.stanford.edu/~afn/gdb_stl_utils/ ) but it is long unmaintained and it works only with SGI's STL implementation, which very few GCC users use.

• Iterators: how to display the item the iterator points at (tested on gdb 6 with a list):print *(iter._M_current)