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std::basic_istream(3)	       C++ Standard Libary	   std::basic_istream(3)

NAME
     std::basic_istream - std::basic_istream

Synopsis
	Defined in header <istream>
	template<

	    class CharT,
	    class Traits = std::char_traits<CharT>

	> class basic_istream : virtual public std::basic_ios<CharT, Traits>

	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>

Global objects
	Two global basic_istream objects are provided by the standard library.

	Defined in header <iostream>
	cin  reads from the standard C input stream stdin
	wcin (global object)

Member types
	Member type Definition
	char_type   CharT
	traits_type Traits; the program is ill-formed  if  Traits::char_type  is
     not
		    CharT.
	int_type    Traits::int_type
	pos_type    Traits::pos_type
	off_type    Traits::off_type

Member functions
	constructor   constructs the object
		      (public member function)
	destructor    destructs the object
	[virtual]     (virtual public member function)
	operator=     move-assigns from another basic_istream
	(C++11)       (protected member function)

Formatted input
	operator>>    extracts formatted data
		      (public member function)

Unformatted input
	get	      extracts characters
		      (public member function)
	peek	      reads the next character without extracting it
		      (public member function)
	unget	      unextracts a character
		      (public member function)
	putback       puts a character into input stream
		      (public member function)
	getline       extracts characters until the given character is found
		      (public member function)
	ignore	      extracts and discards characters until the given character
     is found
		      (public member function)
	read	      extracts blocks of characters
		      (public member function)
	readsome      extracts already available blocks of characters
		      (public member function)
		      returns number of characters extracted by last unformatted
     input
	gcount	      operation
		      (public member function)

Positioning
	tellg	      returns the input position indicator
		      (public member function)
	seekg	      sets the input position indicator
		      (public member function)

Miscellaneous
	sync	      synchronizes with the underlying storage device
		      (public member function)
	swap	      swaps stream objects, except for the associated buffer
	(C++11)       (protected member function)

Member classes
	sentry	implements  basic  logic for preparation of the stream for input
     operations
	       (public member class)

Non-member functions
	operator>>(std::basic_istream) extracts characters and character arrays
				       (function template)

     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>)
	eof	      checks if end-of-file has been reached
		      (public member function of std::basic_ios<CharT,Traits>)
	fail	      checks if an error has occurred
		      (public member function of std::basic_ios<CharT,Traits>)
	bad	      checks if a non-recoverable error has occurred
		      (public member function of std::basic_ios<CharT,Traits>)
	operator!     checks if an error has occurred (synonym of fail())
		      (public member function of std::basic_ios<CharT,Traits>)
	operator bool checks if no error has occurred (synonym of !fail())
		      (public member function of std::basic_ios<CharT,Traits>)
	rdstate       returns state flags
		      (public member function of std::basic_ios<CharT,Traits>)
	setstate      sets state flags
		      (public member function of std::basic_ios<CharT,Traits>)
	clear	      modifies state flags
		      (public member function of std::basic_ios<CharT,Traits>)

Formatting
	copyfmt       copies formatting information
		      (public member function of std::basic_ios<CharT,Traits>)
	fill	      manages the fill character
		      (public member function of std::basic_ios<CharT,Traits>)

Miscellaneous
	exceptions    manages exception mask
		      (public member function of std::basic_ios<CharT,Traits>)
	imbue	      sets the locale
		      (public member function of std::basic_ios<CharT,Traits>)
	rdbuf	      manages associated stream buffer
		      (public member function of std::basic_ios<CharT,Traits>)
	tie	      manages tied stream
		      (public member function of std::basic_ios<CharT,Traits>)
	narrow	      narrows characters
		      (public member function of std::basic_ios<CharT,Traits>)
	widen	      widens characters
		      (public member function of std::basic_ios<CharT,Traits>)

     Inherited from std::ios_base

Member functions
Formatting
	flags		  manages format flags
			  (public member function of std::ios_base)
	setf		  sets specific format flag
			  (public member function of std::ios_base)
	unsetf		  clears specific format flag
			  (public member function of std::ios_base)
	precision	  manages decimal precision of floating point operations
			  (public member function of std::ios_base)
	width		  manages field width
			  (public member function of std::ios_base)

Locales
	imbue		  sets locale
			  (public member function of std::ios_base)
	getloc		  returns current locale
			  (public member function of std::ios_base)

Internal extensible array
	xalloc		   returns a program-wide unique integer that is safe to
     use as index
	[static]	  to pword() and iword()
			  (public static member function of std::ios_base)
			  resizes the private storage if necessary and access to
     the long
	iword		  element at the given index
			  (public member function of std::ios_base)
			  resizes the private storage if necessary and access to
     the void*
	pword		  element at the given index
			  (public member function of std::ios_base)

Miscellaneous
	register_callback registers event callback function
			  (public member function of std::ios_base)
	sync_with_stdio   sets whether C++ and C I/O libraries are interoperable
	[static]	  (public static member function of std::ios_base)

Member classes
	failure 	  stream exception
			  (public member class of std::ios_base)
	Init		  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:

		       Constant 	 Explanation
		       app		 seek to the end of stream  before  each
     write
		       binary		 open in binary mode
	openmode       in		 open for reading
		       out		 open for writing
		       trunc		 discard the contents of the stream when
					 opening
		       ate		  seek	to the end of stream immediately
     after
					 open
		       noreplace (C++23) open in exclusive mode

		       (typedef)
		       formatting flags type

		       The following constants are also defined:

		       Constant    Explanation
		       dec	    use  decimal  base	for  integer  I/O:   see
     std::dec
		       oct	   use octal base for integer I/O: see std::oct
		       hex	    use  hexadecimal  base  for integer I/O: see
     std::hex
		       basefield   dec | oct | hex. Useful  for  masking  opera-
     tions
		       left	    left adjustment (adds fill characters to the
     right): see
				   std::left
		       right	   right adjustment (adds fill characters to the
     left): see
				   std::right
		       internal    internal adjustment (adds fill characters  to
     the internal
				   designated point): see std::internal
		       adjustfield left | right | internal. Useful for masking
				   operations
				   generate  floating  point  types using scien-
     tific notation,
		       scientific  or hex notation if combined with fixed: see
				   std::scientific
	fmtflags		   generate floating point types using fixed no-
     tation, or
		       fixed	   hex notation if combined with scientific: see
				   std::fixed
		       floatfield  scientific | fixed. Useful for masking opera-
     tions
		       boolalpha   insert and extract bool type in  alphanumeric
     format: see
				   std::boolalpha
				   generate a prefix indicating the numeric base
     for integer
		       showbase     output,  require  the  currency indicator in
     monetary I/O:
				   see std::showbase
		       showpoint   generate a decimal-point  character	uncondi-
     tionally for
				   floating-point  number output: see std::show-
     point
		       showpos	   generate a + character for  non-negative  nu-
     meric output:
				   see std::showpos
		       skipws	    skip leading whitespace before certain input
     operations:
				   see std::skipws
		       unitbuf	   flush the output after each output operation:
     see
				   std::unitbuf
				   replace certain lowercase letters with  their
     uppercase
		       uppercase   equivalents in certain output operations: see
				   std::uppercase

		       (typedef)
		       state of the stream type

		       The following constants are also defined:

		       Constant Explanation
	iostate        goodbit	no error
		       badbit	irrecoverable stream error
		       failbit	input/output operation failed (formatting or ex-
     traction
				error)
		       eofbit	 associated  input  sequence has reached end-of-
     file

		       (typedef)
		       seeking direction type

		       The following constants are also defined:

	seekdir        Constant Explanation
		       beg	the beginning of a stream
		       end	the ending of a stream
		       cur	the current position of stream position  indica-
     tor

		       (typedef)
	event	       specifies event type
		       (enum)
	event_callback callback function type
		       (typedef)

http://cppreference.com 	   2024.06.10		   std::basic_istream(3)
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