std::basic_istream
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Input/output library
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(C++23)
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Streams
Abstractions
basic_istream
File I/O
String I/O
Array I/O
(C++23)
(C++23)
(C++23)
(C++98/26*)
(C++98/26*)
(C++98/26*)
Synchronized Output
(C++20)
Types
Error category interface
(C++11)
(C++11)
std::basic_istream
Global objects
Member functions
(C++11)
Formatted input
Unformatted input
Positioning
Miscellaneous
(C++11)
Member classes
Non-member functions
Defined in header
<istream>
template<
class CharT,
class Traits = std::char_traits <CharT>
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().
std-basic istream-inheritance.svg
Inheritance diagram
Several typedefs for common character types are provided:
Defined in header
<istream> Type
Definition
std::istream
std::basic_istream<char>
std::wistream
std::basic_istream<wchar_t>
Contents
[edit] Global objects
Two global basic_istream objects are provided by the standard library.
Defined in header
<iostream> [edit] Member types
Member type
Definition
[edit] Member functions
Formatted input
Unformatted input
returns number of characters extracted by last unformatted input operation
(public member function) [edit]
(public member function) [edit]
Positioning
Miscellaneous
[edit] Member classes
implements basic logic for preparation of the stream for input operations
(public member class) [edit]
(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
checks if no error has occurred i.e. I/O operations are available
(public member function of
(public member function of
std::basic_ios<CharT,Traits>) [edit]
checks if end-of-file has been reached
(public member function of
(public member function of
std::basic_ios<CharT,Traits>) [edit]
checks if a non-recoverable error has occurred
(public member function of
(public member function of
std::basic_ios<CharT,Traits>) [edit]
checks if an error has occurred (synonym of fail() )
(public member function of
(public member function of
std::basic_ios<CharT,Traits>) [edit]
checks if no error has occurred (synonym of
(public member function of
!fail() ) (public member function of
std::basic_ios<CharT,Traits>) [edit]
Formatting
Miscellaneous
Inherited from std::ios_base
Member functions
Formatting
manages decimal precision of floating point operations
(public member function of
(public member function of
std::ios_base) [edit]
Locales
Internal extensible array
[static]
(public static member function of
std::ios_base) [edit]
resizes the private storage if necessary and access to the long element at the given index
(public member function of
(public member function of
std::ios_base) [edit]
resizes the private storage if necessary and access to the void* element at the given index
(public member function of
(public member function of
std::ios_base) [edit]
Miscellaneous
[static]
(public static member function of
std::ios_base) [edit]
Member classes
Member types and constants
Type
Explanation
stream open mode type
(typedef) [edit]
The following constants are also defined:
Constant
Explanation[edit]
(typedef) [edit]
formatting flags type
(typedef) [edit]
The following constants are also defined:
Constant
Explanation[edit]
internal
internal adjustment (adds fill characters to the internal designated point): see std::internal [edit]
scientific
generate floating point types using scientific notation, or hex notation if combined with fixed: see std::scientific [edit]
fixed
generate floating point types using fixed notation, or hex notation if combined with scientific: see std::fixed [edit]
showbase
generate a prefix indicating the numeric base for integer output, require the currency indicator in monetary I/O: see std::showbase [edit]
showpoint
generate a decimal-point character unconditionally for floating-point number output: see std::showpoint [edit]
uppercase
replace certain lowercase letters with their uppercase equivalents in certain output operations: see std::uppercase [edit]
(typedef) [edit]
state of the stream type
(typedef) [edit]
The following constants are also defined:
Constant
Explanation[edit]
(typedef) [edit]