The _S_refcount is there for when you would call ios_base::Init::Init() manually from a constructor of a static class, it protects against double initialization. cerr::tie() and wcerr::tie() are overspecified. The standard streams are constructed once only and never New (&buf_cerr_sync) stdio_sync_filebuf(stderr) New (&buf_cin_sync) stdio_sync_filebuf(stdin) New (&buf_cout_sync) stdio_sync_filebuf(stdout) Standard streams default to synced with "C" operations. If (_gnu_cxx::_exchange_and_add_dispatch(&_S_refcount, 1) = 0) Now we jump to the constructor of ios_base::Init class, in : ios_base::Init::Init() From, this is the important part: // For construction of filebuffers for cout, cin, cerr, clog et. Indirectly) an instance of std::ios_base::Init with static storage The header behaves as if it defines (directly or Std::cout, etc.) are properly initialized and destructed. This class is used to ensure that the default C++ streams (std::cin, std::cout is initialized using a pointer to an instance of some implementation-defined derived class of std::basic_streambuf. Std::basic_ostream has a constructor that takes a pointer to a std::basic_streambuf object. The global objects std::cout and std::wcout control output to a stream buffer of implementation-defined type (derived from std::streambuf), associated with the standard C output stream stdout. As far as I can see, the most related information is: It does not clearly tell me how std::cout is implemented and how std::cout is created by the constructor of std::ostream. This link on CppReference seems not very meaningful. The question arises, since the std::basic_ostream::basic_ostream() is marked protected, how std::cout is created?
#ISTREAM DOES NOT NAME A TYPE CODE#
Here is what the compiler complains about the code snippet above: In file included from /opt/compiler-explorer/gcc-4.9.0/include/c++/4.9.0/iostream:39:0, What's more, it seems that you can't create an instance of std::ostream. I can see the declaration of std::cout in a file named /usr/include/c++/7/iostream: extern ostream cout /// Linked to standard outputĪnd std::ostream is defined by typedef std::basic_ostream std::ostream. Std::cout is an instance of std::ostream.
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