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+[fstream]
+
+# 31 Input/output library [[input.output]](./#input.output)
+
+## 31.10 File-based streams [[file.streams]](file.streams#fstream)
+
+### 31.10.6 Class template basic_fstream [fstream]
+
+#### [31.10.6.1](#general) General [[fstream.general]](fstream.general)
+
+[ð](#lib:basic_fstream)
+
+namespace std {template<class charT, class traits = char_traits<charT>>class basic_fstream : public basic_iostream<charT, traits> {public:using char_type = charT; using int_type = typename traits::int_type; using pos_type = typename traits::pos_type; using off_type = typename traits::off_type; using traits_type = traits; using native_handle_type = typename basic_filebuf<charT, traits>::native_handle_type; // [[fstream.cons]](#cons "31.10.6.2 Constructors"), constructors basic_fstream(); 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]](fstream.syn "31.10.1 Header <fstream> synopsis")explicit basic_fstream(const string& s,
+ ios_base::openmode mode = ios_base::in | ios_base::out); template<class T>explicit basic_fstream(const T& s, ios_base::openmode mode = ios_base::in | ios_base::out);
+ basic_fstream(const basic_fstream&) = delete;
+ basic_fstream(basic_fstream&& rhs);
+
+ basic_fstream& operator=(const basic_fstream&) = delete;
+ basic_fstream& operator=(basic_fstream&& rhs); // [[fstream.swap]](#swap "31.10.6.3 Swap"), swapvoid swap(basic_fstream& rhs); // [[fstream.members]](#members "31.10.6.4 Member functions"), members basic_filebuf<charT, traits>* rdbuf() const;
+ native_handle_type native_handle() const noexcept; bool is_open() const; 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]](fstream.syn "31.10.1 Header <fstream> synopsis")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); void close(); private: basic_filebuf<charT, traits> *sb*; // *exposition only*};}
+
+[1](#general-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12347)
+
+The
+class templatebasic_fstream<charT, traits> supports reading and writing from named files[.](#general-1.sentence-1)
+
+It uses abasic_filebuf<charT, traits> object to control the associated sequences[.](#general-1.sentence-2)
+
+For the sake of exposition, the maintained data is presented here as:
+
+- [(1.1)](#general-1.1)
+
+*sb*, the basic_filebuf object[.](#general-1.sentence-3)
+
+#### [31.10.6.2](#cons) Constructors [[fstream.cons]](fstream.cons)
+
+[ð](#lib:basic_fstream,constructor)
+
+`basic_fstream();
+`
+
+[1](#cons-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12369)
+
+*Effects*: Initializes the base class withbasic_iostream<charT, traits>(addressof(*sb*)) ([[iostream.cons]](iostream.cons "31.7.5.7.2 Constructors"))
+and*sb* with basic_filebuf<charT, traits>()[.](#cons-1.sentence-1)
+
+[ð](#lib:basic_fstream,constructor_)
+
+`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]](fstream.syn "31.10.1 Header <fstream> synopsis")
+`
+
+[2](#cons-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12388)
+
+*Effects*: Initializes the base class withbasic_iostream<charT, traits>(addressof(*sb*)) ([[iostream.cons]](iostream.cons "31.7.5.7.2 Constructors"))
+and*sb* with basic_filebuf<charT, traits>()[.](#cons-2.sentence-1)
+
+Then callsrdbuf()->open(s, mode)[.](#cons-2.sentence-2)
+
+If that function returns a null pointer, callssetstate(failbit)[.](#cons-2.sentence-3)
+
+[ð](#lib:basic_fstream,constructor__)
+
+`explicit basic_fstream(
+  const string& s,
+  ios_base::openmode mode = ios_base::in | ios_base::out);
+`
+
+[3](#cons-3)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12408)
+
+*Effects*: Equivalent to basic_fstream(s.c_str(), mode)[.](#cons-3.sentence-1)
+
+[ð](#lib:basic_fstream,constructor___)
+
+`template<class T>
+  explicit basic_fstream(const T& s, ios_base::openmode mode = ios_base::in | ios_base::out);
+`
+
+[4](#cons-4)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12420)
+
+*Constraints*: is_same_v<T, filesystem::path> is true[.](#cons-4.sentence-1)
+
+[5](#cons-5)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12424)
+
+*Effects*: Equivalent to basic_fstream(s.c_str(), mode)[.](#cons-5.sentence-1)
+
+[ð](#lib:basic_fstream,constructor____)
+
+`basic_fstream(basic_fstream&& rhs);
+`
+
+[6](#cons-6)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12435)
+
+*Effects*: Move constructs the base class, and the contained basic_filebuf[.](#cons-6.sentence-1)
+
+Then calls basic_istream<charT, traits>::set_rdbuf(addressof(*sb*)) to install the contained basic_filebuf[.](#cons-6.sentence-2)
+
+#### [31.10.6.3](#swap) Swap [[fstream.swap]](fstream.swap)
+
+[ð](#lib:swap,basic_fstream)
+
+`void swap(basic_fstream& rhs);
+`
+
+[1](#swap-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12450)
+
+*Effects*: Exchanges the state of *this and rhs by callingbasic_iostream<charT,traits>::swap(rhs) and*sb*.swap(rhs.*sb*)[.](#swap-1.sentence-1)
+
+[ð](#lib:swap,basic_fstream_)
+
+`template<class charT, class traits>
+  void swap(basic_fstream<charT, traits>& x,
+            basic_fstream<charT, traits>& y);
+`
+
+[2](#swap-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12466)
+
+*Effects*: Equivalent to x.swap(y)[.](#swap-2.sentence-1)
+
+#### [31.10.6.4](#members) Member functions [[fstream.members]](fstream.members)
+
+[ð](#lib:rdbuf,basic_fstream)
+
+`basic_filebuf<charT, traits>* rdbuf() const;
+`
+
+[1](#members-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12479)
+
+*Returns*: const_cast<basic_filebuf<charT, traits>*>(addressof(*sb*))[.](#members-1.sentence-1)
+
+[ð](#lib:native_handle,basic_fstream)
+
+`native_handle_type native_handle() const noexcept;
+`
+
+[2](#members-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12490)
+
+*Effects*: Equivalent to: return rdbuf()->native_handle();
+
+[ð](#lib:is_open,basic_fstream)
+
+`bool is_open() const;
+`
+
+[3](#members-3)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12501)
+
+*Returns*: rdbuf()->is_open()[.](#members-3.sentence-1)
+
+[ð](#lib:open,basic_fstream)
+
+`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]](fstream.syn "31.10.1 Header <fstream> synopsis")
+`
+
+[4](#members-4)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12517)
+
+*Effects*: Callsrdbuf()->open(s, mode)[.](#members-4.sentence-1)
+
+If that function does not return a null pointer calls clear(),
+otherwise callssetstate(failbit) (which may throwios_base::failure) ([[iostate.flags]](iostate.flags "31.5.4.4 Flags functions"))[.](#members-4.sentence-2)
+
+[ð](#lib:open,basic_fstream_)
+
+`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);
+`
+
+[5](#members-5)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12539)
+
+*Effects*: Calls open(s.c_str(), mode)[.](#members-5.sentence-1)
+
+[ð](#lib:close,basic_fstream)
+
+`void close();
+`
+
+[6](#members-6)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L12550)
+
+*Effects*: Callsrdbuf()->close() and, if that function
+returns a null pointer,
+callssetstate(failbit) (which may throwios_base::failure) ([[iostate.flags]](iostate.flags "31.5.4.4 Flags functions"))[.](#members-6.sentence-1)