Question

I want to browse the source code of gnu implementation of C++ standard libraries — header files as well as the implementation.
I have landed myself into:

http://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-4.4/index.html

My first step was to look header file at:

http://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-4.4/a01376.html

My question is that as per my understanding the typedeffed string sth like:
typedef basic_string string;
should have been present in string header, but I don’t see one here.

Questions:
–in which file is the definition of string symbol?
–I see that string header file includes lot many headers and if the typedeffed sring symbol is defined in one of these internal headers, is there a search bar something on this site thru which I can reach to the definition of a symbol straightway. (in case someone has already browsed stuff from this site before)

Thanks,
Jagrati

Answer 1

A lot of libstdc++ is implemented using only headers, but some parts of the STL, like std::basic_string, have compiled implementations.

The declaration of template std::basic_string is located in /usr/include/c++/4.4.4/bits/basic_string.h (replace ‘4.4.4’ with g++ -dumpversion) and the implementation is in /usr/include/c++/4.4.4/bits/basic_string.tcc. The actual typedef of std::string, std::wstring, etc. is in .../bits/stringfwd.h. If you needed to instantiate std::basic_string with other template parameters, for example, then you do something like:

#include <bits/basic_string.tcc>

template class std::basic_string<long>;

The way that libstdc++ implements sets and maps (header-only) is kind of interesting, but also very complex because it uses a custom red-black tree implementation (_Rb_tree).

The libstdc++ implementation of std::vector (also header-only) is more self-contained, so it’s worth a glance in /usr/include/c++/4.4.4/bits/stl_vector.h to give you an idea of the internals of libstdc++. Another interesting file is .../bits/stl_algo.h, which contains the definitions of STL algorithms.

Note: On Windows with MinGW, you’ll find the libstdc++ headers in lib\gcc\mingw32\4.4.0\include\c++\bits of your MinGW installation, replacing ‘4.4.0’ with g++ -dumpversion.