Standard library header <fstream>

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library(C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library(C++17)

Regular expressions library(C++11)

Atomic operations library(C++11)

Thread support library(C++11)

Technical Specifications

 

Standard Library headers

Language Support
<cstddef> <cstdlib> <version> <limits> <climits>	<cfloat> <cstdint> <new> <typeinfo>	<source_location> <exception> <initializer_list> <compare>	<coroutine> <csignal> <csetjmp> <cstdarg>
Concepts
<concepts>
Diagnostics
<stdexcept>	<cassert>	<cerrno>	<system_error>
General utilities
<utility> <memory> <memory_resource> <scoped_allocator>	<bitset> <tuple> <optional> <any>	<variant> <type_traits> <ratio> <chrono>	<typeindex> <functional> <ctime>
Strings
<string> <string_view> <cstring>	<charconv> <format>	<cctype> <cwctype>	<cwchar> <cuchar>
Localization
<locale>	<codecvt>	<clocale>
Containers
<span> <array> <vector>	<deque> <forward_list> <list>	<map> <set> <queue>	<unordered_map> <unordered_set> <stack>
Iterators
<iterator>
Ranges
<ranges>
Algorithms
<algorithm>	<execution>
Numerics
<complex> <random>	<valarray> <numeric>	<bit> <numbers>	<cfenv> <cmath>
Input/Output
<iosfwd> <ios> <iomanip> <streambuf>	<istream> <ostream> <iostream>	<sstream> <fstream> <syncstream>	<cstdio> <cinttypes> <strstream>
Regular expressions
<regex>
Filesystem support
<filesystem>
Thread support
<thread> <atomic> <mutex>	<shared_mutex> <condition_variable> <future>	<stop_token> <semaphore>	<latch> <barrier>
C compatibility
<ciso646> <cstdalign>	<cstdbool> <ccomplex>	<ctgmath>

 

This header is part of the Input/Output library.

Classes
basic_filebuf	implements raw file device (class template)
basic_ifstream	implements high-level file stream input operations (class template)
basic_ofstream	implements high-level file stream output operations (class template)
basic_fstream	implements high-level file stream input/output operations (class template)
filebuf	std::basic_filebuf<char> (typedef)
wfilebuf	std::basic_filebuf<wchar_t> (typedef)
ifstream	std::basic_ifstream<char> (typedef)
wifstream	std::basic_ifstream<wchar_t> (typedef)
ofstream	std::basic_ofstream<char> (typedef)
wofstream	std::basic_ofstream<wchar_t> (typedef)
fstream	std::basic_fstream<char> (typedef)
wfstream	std::basic_fstream<wchar_t> (typedef)
Functions
std::swap(std::basic_filebuf) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::basic_ifstream) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::basic_ofstream) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::basic_fstream) (C++11)	specializes the std::swap algorithm (function template)

Synopsis

namespace std {template<class charT, class traits = char_traits<charT>>class basic_filebuf;using filebuf = basic_filebuf<char>;using wfilebuf = basic_filebuf<wchar_t>;   template<class charT, class traits = char_traits<charT>>class basic_ifstream;using ifstream = basic_ifstream<char>;using wifstream = basic_ifstream<wchar_t>;   template<class charT, class traits = char_traits<charT>>class basic_ofstream;using ofstream = basic_ofstream<char>;using wofstream = basic_ofstream<wchar_t>;   template<class charT, class traits = char_traits<charT>>class basic_fstream;using fstream = basic_fstream<char>;using wfstream = basic_fstream<wchar_t>;}

Class template std::basic_filebuf

namespace std {template<class CharT, class Traits = char_traits<CharT>>class basic_filebuf :public basic_streambuf<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;   // constructors/destructor basic_filebuf(); basic_filebuf(const basic_filebuf&)= delete; basic_filebuf(basic_filebuf&& rhs);virtual ~basic_filebuf();   // assign and swap basic_filebuf& operator=(const basic_filebuf&)= delete; basic_filebuf& operator=(basic_filebuf&& rhs);void swap(basic_filebuf& rhs);   // membersbool is_open()const; basic_filebuf* open(constchar* s, ios_base::openmode mode); basic_filebuf* open(const filesystem::path::value_type* s, ios_base::openmode mode);// wide systems only basic_filebuf* open(const string& s, ios_base::openmode mode); basic_filebuf* open(const filesystem::path& s, ios_base::openmode mode); basic_filebuf* close();   protected:// overridden virtual functions streamsize showmanyc() override; int_type underflow() override; int_type uflow() override; int_type pbackfail(int_type c = Traits::eof()) override; int_type overflow (int_type c = Traits::eof()) override;   basic_streambuf<CharT, Traits>* setbuf(char_type* s, streamsize n) override; pos_type seekoff(off_type off, ios_base::seekdir way, ios_base::openmode which = ios_base::in| ios_base::out) override; pos_type seekpos(pos_type sp, ios_base::openmode which = ios_base::in| ios_base::out) override;int sync() override;void imbue(const locale& loc) override;};   template<class CharT, class Traits>void swap(basic_filebuf<CharT, Traits>& x, basic_filebuf<CharT, Traits>& y);}

Class template std::basic_ifstream

namespace std {template<class CharT, class Traits = char_traits<CharT>>class basic_ifstream :public basic_istream<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;   // constructors basic_ifstream();explicit basic_ifstream(constchar* s, ios_base::openmode mode = ios_base::in);explicit basic_ifstream(const filesystem::path::value_type* s, ios_base::openmode mode = ios_base::in);// wide systems onlyexplicit basic_ifstream(const string& s, ios_base::openmode mode = ios_base::in);explicit basic_ifstream(const filesystem::path& s, ios_base::openmode mode = ios_base::in); basic_ifstream(const basic_ifstream&)= delete; basic_ifstream(basic_ifstream&& rhs);   // assign and swap basic_ifstream& operator=(const basic_ifstream&)= delete; basic_ifstream& operator=(basic_ifstream&& rhs);void swap(basic_ifstream& rhs);   // members basic_filebuf<CharT, Traits>* rdbuf()const;   bool is_open()const;void open(constchar* s, ios_base::openmode mode = ios_base::in);void open(const filesystem::path::value_type* s, ios_base::openmode mode = ios_base::in);// wide systems onlyvoid open(const string& s, ios_base::openmode mode = ios_base::in);void open(const filesystem::path& s, ios_base::openmode mode = ios_base::in);void close();private: basic_filebuf<CharT, Traits> sb;// exposition only};   template<class CharT, class Traits>void swap(basic_ifstream<CharT, Traits>& x, basic_ifstream<CharT, Traits>& y);}

Class template std::basic_ofstream

namespace std {template<class CharT, class Traits = char_traits<CharT>>class basic_ofstream :public basic_ostream<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;   // constructors basic_ofstream();explicit basic_ofstream(constchar* s, ios_base::openmode mode = ios_base::out);explicit basic_ofstream(const filesystem::path::value_type* s, // wide systems only ios_base::openmode mode = ios_base::out);explicit basic_ofstream(const string& s, ios_base::openmode mode = ios_base::out);explicit basic_ofstream(const filesystem::path& s, ios_base::openmode mode = ios_base::out); basic_ofstream(const basic_ofstream&)= delete; basic_ofstream(basic_ofstream&& rhs);   // assign and swap basic_ofstream& operator=(const basic_ofstream&)= delete; basic_ofstream& operator=(basic_ofstream&& rhs);void swap(basic_ofstream& rhs);   // members basic_filebuf<CharT, Traits>* rdbuf()const;   bool is_open()const;void open(constchar* s, ios_base::openmode mode = ios_base::out);void open(const filesystem::path::value_type* s, ios_base::openmode mode = ios_base::out);// wide systems onlyvoid open(const string& s, ios_base::openmode mode = ios_base::out);void open(const filesystem::path& s, ios_base::openmode mode = ios_base::out);void close();private: basic_filebuf<CharT, Traits> sb;// exposition only};   template<class CharT, class Traits>void swap(basic_ofstream<CharT, Traits>& x, basic_ofstream<CharT, Traits>& y);}

Class template std::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;   // constructors basic_fstream();explicit basic_fstream(constchar* 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 onlyexplicit basic_fstream(const string& s, ios_base::openmode mode = ios_base::in| ios_base::out);explicit basic_fstream(const filesystem::path& s, ios_base::openmode mode = ios_base::in| ios_base::out); basic_fstream(const basic_fstream&)= delete; basic_fstream(basic_fstream&& rhs);   // assign and swap basic_fstream& operator=(const basic_fstream&)= delete; basic_fstream& operator=(basic_fstream&& rhs);void swap(basic_fstream& rhs);   // members basic_filebuf<CharT, Traits>* rdbuf()const;bool is_open()const;void open(constchar* 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 onlyvoid 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};   template<class CharT, class Traits>void swap(basic_fstream<CharT, Traits>& x, basic_fstream<CharT, Traits>& y);}