class
<fstream>
std::fstream
typedef basic_fstream<char> fstream;
Input/output file stream class
Input/output stream class to operate on files.
Objects of this class maintain a filebuf object as their internal stream buffer, which performs input/output operations on the file they are associated with (if any).
File streams are associated with files either on construction, or by calling member open.
This is an instantiation of basic_fstream with the following template parameters:
| template parameter | definition | comments |
|---|
| charT | char | Aliased as member char_type |
| traits | char_traits<char> | Aliased as member traits_type |
Apart from the internal file stream buffer, objects of this class keep a set of internal fields inherited from ios_base, ios and istream:
| field | member functions | description |
|---|
| Formatting | format flags | flags
setf
unsetf | A set of internal flags that affect how certain input/output operations are interpreted or generated.
See member type fmtflags. |
| field width | width | Width of the next formatted element to insert. |
| display precision | precision | Decimal precision for the next floating-point value inserted. |
| locale | getloc
imbue | The locale object used by the function for formatted input/output operations affected by localization properties. |
| fill character | fill | Character to pad a formatted field up to the field width (width). |
| State | error state | rdstate
setstate
clear | The current error state of the stream.
Individual values may be obtained by calling good, eof, fail and bad.
See member type iostate. |
| exception mask | exceptions | The state flags for which a failure exception is thrown.
See member type iostate. |
| Other | callback stack | register_callback | Stack of pointers to functions that are called when certain events occur. |
| extensible arrays | iword
pword
xalloc | Internal arrays to store objects of type long and void*. |
| tied stream | tie | Pointer to output stream that is flushed before each i/o operation on this stream. |
| stream buffer | rdbuf | Pointer to the associated streambuf object, which is charge of all input/output operations. |
| character count | gcount | Count of characters read by last unformatted input operation. |
Member types
The class declares the following member types:
These member types are inherited from its base classes istream, ostream and ios_base:
- event
- Type to indicate event type (public member type)
- event_callback
- Event callback function type (public member type)
- failure
- Base class for stream exceptions (public member class)
- fmtflags
- Type for stream format flags (public member type)
- Init
- Initialize standard stream objects (public member class)
- iostate
- Type for stream state flags (public member type)
- openmode
- Type for stream opening mode flags (public member type)
- seekdir
- Type for stream seeking direction flag (public member type)
- sentry (istream)
- Prepare stream for input (public member class)
- sentry (ostream)
- Prepare stream for output (public member class)
Public member functions
- (constructor)
- Construct object and optionally open file (public member function)
- open
- Open file (public member function)
- is_open
- Check if a file is open (public member function)
- close
- Close file (public member function)
- rdbuf
- Get the associated filebuf object (public member function)
- operator=
- Move assignment (public member function)
- swap
- Swap internals (public member function)
Public member functions inherited from istream
- operator>>
- Extract formatted input (public member function)
- gcount
- Get character count (public member function)
- get
- Get characters (public member function)
- getline
- Get line (public member function)
- ignore
- Extract and discard characters (public member function)
- peek
- Peek next character (public member function)
- read
- Read block of data (public member function)
- readsome
- Read data available in buffer (public member function)
- putback
- Put character back (public member function)
- unget
- Unget character (public member function)
- tellg
- Get position in input sequence (public member function)
- seekg
- Set position in input sequence (public member function)
- sync
- Synchronize input buffer (public member function)
Public member functions inherited from ostream
- operator<<
- Insert formatted output (public member function)
- put
- Put character (public member function)
- write
- Write block of data (public member function)
- tellp
- Get position in output sequence (public member function)
- seekp
- Set position in output sequence (public member function)
- flush
- Flush output stream buffer (public member function)
Public member functions inherited from ios
- good
- Check whether state of stream is good (public member function)
- eof
- Check whether eofbit is set (public member function)
- fail
- Check whether either failbit or badbit is set (public member function)
- bad
- Check whether badbit is set (public member function)
- operator!
- Evaluate stream (not) (public member function)
- operator bool
- Evaluate stream (public member function)
- rdstate
- Get error state flags (public member function)
- setstate
- Set error state flag (public member function)
- clear
- Set error state flags (public member function)
- copyfmt
- Copy formatting information (public member function)
- fill
- Get/set fill character (public member function)
- exceptions
- Get/set exceptions mask (public member function)
- imbue
- Imbue locale (public member function)
- tie
- Get/set tied stream (public member function)
- rdbuf
- Get/set stream buffer (public member function)
- narrow
- Narrow character (public member function)
- widen
- Widen character (public member function)
Public member functions inherited from ios_base
- flags
- Get/set format flags (public member function)
- setf
- Set specific format flags (public member function)
- unsetf
- Clear specific format flags (public member function)
- precision
- Get/Set floating-point decimal precision (public member function)
- width
- Get/set field width (public member function)
- imbue
- Imbue locale (public member function)
- getloc
- Get current locale (public member function)
- xalloc
- Get new index for extensible array [static] (public static member function)
- iword
- Get integer element of extensible array (public member function)
- pword
- Get pointer element of extensible array (public member function)
- register_callback
- Register event callback function (public member function)
- sync_with_stdio
- Toggle synchronization with cstdio streams [static] (public static member function)
Non-member function overloads
- swap
- Swap file streams (function template)