How to pretty-print STL containers in GDB?

by

It just works on Ubuntu 17.04

Debian seems to have finally integrated things properly now:

main.cpp

#include <map>
#include <utility>
#include <vector>

int main() {
    std::vector<int> v;
    v.push_back(0);
    v.push_back(1);
    v.push_back(2);
    std::map<int,int> m;
    m.insert(std::make_pair(0, 0));
    m.insert(std::make_pair(1, -1));
    m.insert(std::make_pair(2, -2));
}

Compile:

g++ -O0 -ggdb3 -o main.out -std=c++98 main.cpp

Outcome:

(gdb) p v
$1 = std::vector of length 3, capacity 4 = {0, 1, 2}
(gdb) p m
$2 = std::map with 3 elements = {[0] = 0, [1] = -1, [2] = -2}

We can see that the pretty printer is installed with:

(gdb) info pretty-printer

Which contains the lines:

global pretty-printers:
  objfile /usr/lib/x86_64-linux-gnu/libstdc++.so.6 pretty-printers:
  libstdc++-v6
    std::map
    std::vector

The printers are provided by the file:

/usr/share/gcc-7/python/libstdcxx/v6/printers.py

which comes with the main C++ library package libstdc++6 and is located under libstdc++-v3/python/libstdcxx in the GCC source code:
https://github.com/gcc-mirror/gcc/blob/releases/gcc-6.3.0/libstdc%2B%2B-v3/python/libstdcxx/v6/printers.py#L244

TODO: how GDB finds that file is the final mistery, it is not in my Python path: python -c "import sys; print('\n'.join(sys.path))" so it must be hardcoded somewhere?

Custom classes

See how to define a custom toString method and call it at: Printing C++ class objects with GDB

Inspect specific elements in optimized code

It was hard last time I checked, you get “Cannot evaluate function — may be in-lined” C++, STL, GDB: Cannot evaluate function maybe inlined

On unoptimized code it works: Inspecting standard container (std::map) contents with gdb

More Related Contents:

  1. Debugging core files generated on a Customer’s box
  2. How do I print the elements of a C++ vector in GDB?
  3. What’s the difference between 'gcc -g' and 'gcc -g3'?
  4. Can I set a breakpoint on ‘memory access’ in GDB?
  5. Inspecting standard container (std::map) contents with gdb
  6. Run an Application in GDB Until an Exception Occurs
  7. How do I print the full value of a long string in gdb?
  8. How to solve “ptrace operation not permitted” when trying to attach GDB to a process?
  9. Cannot insert breakpoints. Addresses with low values
  10. How to set breakpoints on future shared libraries with a command flag
  11. How to get a “codesigned” gdb on OSX?
  12. How to set a breakpoint in GDB where the function returns?
  13. How do I pass a command line argument while starting up GDB in Linux? [duplicate]
  14. How do I use the MinGW gdb debugger to debug a C++ program in Windows?
  15. How to pass arguments and redirect stdin from a file to program run in gdb?
  16. Inspecting STL containers in Visual Studio debugging
  17. How to avoid entering library’s source files while debugging in Qt Creator with gdb?
  18. Can standard container templates be instantiated with incomplete types?
  19. Sort list using STL sort function
  20. What does the standard library guarantee about self move assignment?
  21. How can I tell if a library was compiled with -g?
  22. std::optional specialization for reference types
  23. What is the past-the-end iterator in STL C++?
  24. Detect Windows or Linux in C, C++ [duplicate]
  25. How to make reading from `std::cin` timeout after a particular amount of time
  26. What is Linux’s native GUI API?
  27. How to use the priority queue STL for objects?
  28. Should you overload swap in the std namespace?
  29. Is it more efficient to copy a vector by reserving and copying, or by creating and swapping? [duplicate]
  30. Obtain container type from (its) iterator type in C++ (STL)

Leave a Comment