31 Input/output library [input.output]

31.10 File-based streams [file.streams]

31.10.5 Class template basic_fstream [fstream]

31.10.5.4 Member functions [fstream.members]

basic_filebuf<charT, traits>* rdbuf() const;
Returns: const_cast<basic_filebuf<charT, traits>*>(addressof(sb)).
bool is_open() const;
Returns: rdbuf()->is_open().
void open( const char* s, ios_base::openmode mode = ios_base::in | ios_base::out); void open( const filesystem::path::value_type* s, ios_base::openmode mode = ios_base::in | ios_base::out); // wide systems only; see [fstream.syn]
Effects: Calls rdbuf()->open(s, mode).
If that function does not return a null pointer calls clear(), otherwise calls setstate(failbit) (which may throw ios_base​::​failure) ([iostate.flags]).
void open( const string& s, ios_base::openmode mode = ios_base::in | ios_base::out); void open( const filesystem::path& s, ios_base::openmode mode = ios_base::in | ios_base::out);
Effects: Calls open(s.c_str(), mode).
void close();
Effects: Calls rdbuf()->close() and, if that function returns a null pointer, calls setstate(failbit) (which may throw ios_base​::​failure) ([iostate.flags]).