std::basic_istream - cppreference.com (original) (raw)
The class template basic_istream provides support for high level input operations on character streams. The supported operations include formatted input (e.g. integer values or whitespace-separated characters and characters strings) and unformatted input (e.g. raw characters and character arrays). This functionality is implemented in terms of the interface provided by the underlying basic_streambuf class, accessed through the basic_ios base class. The only non-inherited data member of basic_istream, in most implementations, is the value returned by basic_istream::gcount().
Inheritance diagram
Several typedefs for common character types are provided:
| Type | Definition |
| std::istream | std::basic_istream<char> |
| std::wistream | std::basic_istream<wchar_t> |
Contents
- 1 Global objects
- 2 Member types
- 3 Member functions
- 4 Member classes
- 5 Non-member functions
- 6 Inherited from std::basic_ios
- 7 Inherited from std::ios_base
[edit] Global objects
Two global basic_istream objects are provided by the standard library.
[edit] Member types
| Member type | Definition |
|---|---|
| char_type | CharT[edit] |
| traits_type | Traits; the program is ill-formed if Traits::char_type is not CharT.[edit] |
| int_type | Traits::int_type[edit] |
| pos_type | Traits::pos_type[edit] |
| off_type | Traits::off_type[edit] |
[edit] Member functions
| (constructor) | constructs the object (public member function) [edit] |
|---|---|
| (destructor)[virtual] | destructs the object (virtual public member function) [edit] |
| operator=(C++11) | move-assigns from another basic_istream (protected member function) [edit] |
| Formatted input | |
| operator>> | extracts formatted data (public member function) [edit] |
| Unformatted input | |
| get | extracts characters (public member function) [edit] |
| peek | reads the next character without extracting it (public member function) [edit] |
| unget | unextracts a character (public member function) [edit] |
| putback | puts a character into input stream (public member function) [edit] |
| getline | extracts characters until the given character is found (public member function) [edit] |
| ignore | extracts and discards characters until the given character is found (public member function) [edit] |
| read | extracts blocks of characters (public member function) [edit] |
| readsome | extracts already available blocks of characters (public member function) [edit] |
| gcount | returns number of characters extracted by last unformatted input operation (public member function) [edit] |
| Positioning | |
| tellg | returns the input position indicator (public member function) [edit] |
| seekg | sets the input position indicator (public member function) [edit] |
| Miscellaneous | |
| sync | synchronizes with the underlying storage device (public member function) [edit] |
| swap(C++11) | swaps stream objects, except for the associated buffer (protected member function) [edit] |
[edit] Member classes
| | implements basic logic for preparation of the stream for input operations (public member class) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
[edit] Non-member functions
Inherited from std::basic_ios
Member types
| Member type | Definition |
|---|---|
| char_type | CharT |
| traits_type | Traits |
| int_type | Traits::int_type |
| pos_type | Traits::pos_type |
| off_type | Traits::off_type |
Member functions
| State functions | |
|---|---|
| good | checks if no error has occurred i.e. I/O operations are available (public member function of std::basic_ios<CharT,Traits>) [edit] |
| eof | checks if end-of-file has been reached (public member function of std::basic_ios<CharT,Traits>) [edit] |
| fail | checks if an error has occurred (public member function of std::basic_ios<CharT,Traits>) [edit] |
| bad | checks if a non-recoverable error has occurred (public member function of std::basic_ios<CharT,Traits>) [edit] |
| operator! | checks if an error has occurred (synonym of fail()) (public member function of std::basic_ios<CharT,Traits>) [edit] |
| operator bool | checks if no error has occurred (synonym of |
| rdstate | returns state flags (public member function of std::basic_ios<CharT,Traits>) [edit] |
| setstate | sets state flags (public member function of std::basic_ios<CharT,Traits>) [edit] |
| clear | modifies state flags (public member function of std::basic_ios<CharT,Traits>) [edit] |
| Formatting | |
| copyfmt | copies formatting information (public member function of std::basic_ios<CharT,Traits>) [edit] |
| fill | manages the fill character (public member function of std::basic_ios<CharT,Traits>) [edit] |
| Miscellaneous | |
| exceptions | manages exception mask (public member function of std::basic_ios<CharT,Traits>) [edit] |
| imbue | sets the locale (public member function of std::basic_ios<CharT,Traits>) [edit] |
| rdbuf | manages associated stream buffer (public member function of std::basic_ios<CharT,Traits>) [edit] |
| tie | manages tied stream (public member function of std::basic_ios<CharT,Traits>) [edit] |
| narrow | narrows characters (public member function of std::basic_ios<CharT,Traits>) [edit] |
| widen | widens characters (public member function of std::basic_ios<CharT,Traits>) [edit] |
Inherited from std::ios_base
Member functions
| Formatting | |
|---|---|
| flags | manages format flags (public member function of std::ios_base) [edit] |
| setf | sets specific format flag (public member function of std::ios_base) [edit] |
| unsetf | clears specific format flag (public member function of std::ios_base) [edit] |
| precision | manages decimal precision of floating point operations (public member function of std::ios_base) [edit] |
| width | manages field width (public member function of std::ios_base) [edit] |
| Locales | |
| imbue | sets locale (public member function of std::ios_base) [edit] |
| getloc | returns current locale (public member function of std::ios_base) [edit] |
| Internal extensible array | |
| xalloc[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) [edit] |
| iword | resizes the private storage if necessary and access to the long element at the given index (public member function of std::ios_base) [edit] |
| pword | resizes the private storage if necessary and access to the void* element at the given index (public member function of std::ios_base) [edit] |
| Miscellaneous | |
| register_callback | registers event callback function (public member function of std::ios_base) [edit] |
| sync_with_stdio[static] | sets whether C++ and C I/O libraries are interoperable (public static member function of std::ios_base) [edit] |
| Member classes | |
| failure | stream exception (public member class of std::ios_base) [edit] |
| Init | initializes standard stream objects (public member class of std::ios_base) [edit] |