[fstream.cons]
31 Input/output library [input.output]
31.10 File-based streams [file.streams]
31.10.6 Class template basic_fstream [fstream]
31.10.6.2 Constructors [fstream.cons]
Effects: Initializes the base class with basic_iostream<charT, traits>(addressof(sb)) ([iostream.cons]) and sb with basic_filebuf<charT, traits>().
explicit basic_fstream(
const char* s,
ios_base::openmode mode = ios_base::in | ios_base::out);
explicit basic_fstream(
const filesystem::path::value_type* s,
ios_base::openmode mode = ios_base::in | ios_base::out); // wide systems only; see [fstream.syn]
Effects: Initializes the base class with basic_iostream<charT, traits>(addressof(sb)) ([iostream.cons]) and sb with basic_filebuf<charT, traits>().
Then calls rdbuf()->open(s, mode).
If that function returns a null pointer, calls setstate(failbit).
explicit basic_fstream(
const string& s,
ios_base::openmode mode = ios_base::in | ios_base::out);
Effects: Equivalent to basic_fstream(s.c_str(), mode).
template<class T>
explicit basic_fstream(const T& s, ios_base::openmode mode = ios_base::in | ios_base::out);
Constraints: is_same_v<T, filesystem::path> is true.
Effects: Equivalent to basic_fstream(s.c_str(), mode).
basic_fstream(basic_fstream&& rhs);