30 Input/output library [input.output]

30.5 Iostreams base classes [iostreams.base]

30.5.3 Class ios_­base [ios.base]

30.5.3.1 Types [ios.types]

30.5.3.1.6 Class ios_­base​::​Init [ios::Init]

namespace std {
  class ios_base::Init {
  public:
    Init();
    ~Init();
  private:
    static int init_cnt; // exposition only
  };
}
The class Init describes an object whose construction ensures the construction of the eight objects declared in <iostream> ([iostream.objects]) that associate file stream buffers with the standard C streams provided for by the functions declared in <cstdio>.
For the sake of exposition, the maintained data is presented here as:
  • static int init_­cnt, counts the number of constructor and destructor calls for class Init, initialized to zero.
Init();
Effects: Constructs an object of class Init.
Constructs and initializes the objects cin, cout, cerr, clog, wcin, wcout, wcerr, and wclog if they have not already been constructed and initialized.
~Init();
Effects: Destroys an object of class Init.
If there are no other instances of the class still in existence, calls cout.flush(), cerr.flush(), clog.flush(), wcout.flush(), wcerr.flush(), wclog.flush().