std::basic_fstream
From cppreference.com
Defined in header <fstream>
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template< class CharT, |
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The class template basic_fstream
implements high-level input/output operations on file based streams. It interfaces a file-based streambuffer (std::basic_filebuf) with the high-level interface of (std::basic_iostream).
A typical implementation of std::basic_fstream
holds only one non-derived data member: an instance of std::basic_filebuf<CharT, Traits>.
Two specializations for common character types are also defined:
Defined in header
<fstream> | |
Type | Definition |
fstream
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basic_fstream<char> |
wfstream
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basic_fstream<wchar_t> |
Member types
Member type | Definition |
char_type
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CharT |
traits_type
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Traits |
int_type
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Traits::int_type |
pos_type
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Traits::pos_type |
off_type
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Traits::off_type |
Member functions
constructs the file stream (public member function) | |
(destructor) [virtual] (implicitly declared) |
destructs the basic_fstream and the associated buffer, closes the file (virtual public member function) |
(C++11) |
moves the file stream (public member function) |
(C++11) |
swaps two file streams (public member function) |
returns the underlying raw file device object (public member function) | |
File operations | |
checks if the stream has an associated file (public member function) | |
opens a file and associates it with the stream (public member function) | |
closes the associated file (public member function) |
Non-member functions
specializes the std::swap algorithm (function template) |
Inherited from std::basic_istream
Member functions
Formatted input | |
extracts formatted data (public member function of std::basic_istream ) | |
Unformatted input | |
extracts characters (public member function of std::basic_istream ) | |
reads the next character without extracting it (public member function of std::basic_istream ) | |
unextracts a character (public member function of std::basic_istream ) | |
puts character into input stream (public member function of std::basic_istream ) | |
extracts characters until the given character is found (public member function of std::basic_istream ) | |
extracts and discards characters until the given character is found (public member function of std::basic_istream ) | |
extracts blocks of characters (public member function of std::basic_istream ) | |
extracts already available blocks of characters (public member function of std::basic_istream ) | |
returns number of characters extracted by last unformatted input operation (public member function of std::basic_istream ) | |
Positioning | |
returns the input position indicator (public member function of std::basic_istream ) | |
sets the input position indicator (public member function of std::basic_istream ) | |
Miscellaneous | |
synchronizes with the underlying storage device (public member function of std::basic_istream ) |
Member classes
implements basic logic for preparation of the stream for input operations (public member class of std::basic_istream ) |
Inherited from std::basic_ostream
Member functions
Formatted input | |
inserts formatted data (public member function of std::basic_ostream ) | |
Unformatted input | |
inserts a character (public member function of std::basic_ostream ) | |
inserts blocks of characters (public member function of std::basic_ostream ) | |
Positioning | |
returns the output position indicator (public member function of std::basic_ostream ) | |
sets the output position indicator (public member function of std::basic_ostream ) | |
Miscellaneous | |
synchronizes with the underlying storage device (public member function of std::basic_ostream ) |
Member classes
implements basic logic for preparation of the stream for output operations (public member class of std::basic_ostream ) |
Inherited from std::basic_ios
Member types
Member type | Definition |
char_type
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CharT |
traits_type
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Traits |
int_type
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Traits::int_type |
pos_type
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Traits::pos_type |
off_type
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Traits::off_type |
Member functions
State functions | |
checks if no error has occurred i.e. I/O operations are available (public member function of std::basic_ios ) | |
checks if end-of-file has been reached (public member function of std::basic_ios ) | |
checks if an error has occurred (public member function of std::basic_ios ) | |
checks if a non-recoverable error has occurred (public member function of std::basic_ios ) | |
checks if an error has occurred (synonym of fail()) (public member function of std::basic_ios ) | |
(until C++11)(since C++11) |
checks if no error has occurred (synonym of !fail()) (public member function of std::basic_ios ) |
returns state flags (public member function of std::basic_ios ) | |
sets state flags (public member function of std::basic_ios ) | |
clears error and eof flags (public member function of std::basic_ios ) | |
Formatting | |
copies formatting information (public member function of std::basic_ios ) | |
manages the fill character (public member function of std::basic_ios ) | |
Miscellaneous | |
manages exception mask (public member function of std::basic_ios ) | |
sets the locale (public member function of std::basic_ios ) | |
manages associated stream buffer (public member function of std::basic_ios ) | |
manages tied stream (public member function of std::basic_ios ) | |
narrows characters (public member function of std::basic_ios ) | |
widens characters (public member function of std::basic_ios ) |
Inherited from std::ios_base
Member functions
Formatting | |
manages format flags (public member function of std::ios_base ) | |
sets specific format flag (public member function of std::ios_base ) | |
clears specific format flag (public member function of std::ios_base ) | |
manages decimal precision of floating point operations (public member function of std::ios_base ) | |
manages field width (public member function of std::ios_base ) | |
Locales | |
sets locale (public member function of std::ios_base ) | |
returns current locale (public member function of std::ios_base ) | |
Internal extensible array | |
[static] |
returns a program-wide unique integer that is safe to use as index to pword() and iword() (public static member function of std::ios_base ) |
resizes the private storage if necessary and access to the long element at the given index (public member function of std::ios_base ) | |
resizes the private storage if necessary and access to the void* element at the given index (public member function of std::ios_base ) | |
Miscellaneous | |
registers event callback function (public member function of std::ios_base ) | |
[static] |
sets whether C++ and C IO libraries are interoperable (public static member function of std::ios_base ) |
Member classes | |
stream exception (public member class of std::ios_base ) | |
initializes standard stream objects (public member class of std::ios_base ) |
Member types and constants | |||||||||||||||||||||||||||||||||||||||
Type | Explanation | ||||||||||||||||||||||||||||||||||||||
stream open mode type
The following constants are also defined:
(typedef) | |||||||||||||||||||||||||||||||||||||||
formatting flags type
The following constants are also defined:
(typedef) | |||||||||||||||||||||||||||||||||||||||
state of the stream type
The following constants are also defined:
(typedef) | |||||||||||||||||||||||||||||||||||||||
seeking direction type
The following constants are also defined:
(typedef) | |||||||||||||||||||||||||||||||||||||||
specifies event type (enum) | |||||||||||||||||||||||||||||||||||||||
callback function type (typedef) |
See also
read data from an I/O stream into a string (function template) |
Example
Run this code
#include <iostream> #include <fstream> #include <string> int main() { std::string filename = "test.bin"; std::fstream s(filename, s.binary | s.trunc | s.in | s.out); if (!s.is_open()) { std::cout << "failed to open " << filename << '\n'; } else { // write double d = 3.14; s.write(reinterpret_cast<char*>(&d), sizeof d); // binary output s << 123 << "abc"; // text output // for fstream, this moves the file position pointer (both put and get) s.seekp(0); // read s.read(reinterpret_cast<char*>(&d), sizeof d); // binary input int n; std::string str; if (s >> n >> str) // text input std::cout << "read back from file: " << d << ' ' << n << ' ' << str << '\n'; } }
Output:
read back from file: 3.14 123 abc