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

NAME
       std::istreambuf_iterator	- std::istreambuf_iterator

Synopsis
	  Defined in header <iterator>
	  template< class CharT, class Traits =	std::char_traits<CharT>	>

	  class	istreambuf_iterator : public std::iterator<
	  std::input_iterator_tag,
	  CharT,
       (until C++17)
	  typename Traits::off_type,
	  /* unspecified, usually CharT* */,

	  CharT	>
	  template<  class  CharT,  class  Traits  = std::char_traits<CharT> >
       (since C++17)
	  class	istreambuf_iterator;

	  std::istreambuf_iterator is a	single-pass input iterator that	 reads
       successive
	  characters  from  the	 std::basic_streambuf  object for which	it was
       constructed.

	  The default-constructed std::istreambuf_iterator  is	known  as  the
       end-of-stream
	  iterator.  When  a valid std::istreambuf_iterator reaches the	end of
       the underlying
	  stream, it becomes equal to the end-of-stream	iterator.  Dereferenc-
       ing or
	  incrementing it further invokes undefined behavior.

	  std::istreambuf_iterator has a trivial copy constructor, a constexpr
       (since C++11)
	  default constructor, and a trivial destructor.

Member types
	  Member type	    Definition
	  iterator_category std::input_iterator_tag
	  value_type	    CharT
	  difference_type   Traits::off_type
	  pointer	    /* unspecified, usually CharT* */
	  reference	    CharT
	  char_type	    CharT
	  traits_type	    Traits
	  int_type	    typename traits::int_type
	  streambuf_type    std::basic_streambuf<CharT,	Traits>
	  istream_type	    std::basic_istream<CharT, Traits>
			    Implementation-defined  class type.	The name proxy
       is for
			    exposition only.
	  /* proxy */	    A proxy object holds a char_type character	and  a
       streambuf_type*
			    pointer.
			    Deferencing	 a  proxy object with operator*	yields
       the stored
			    character.

	  Member types iterator_category, value_type, difference_type, pointer
	  and reference	 are  required	to  be	obtained  by  inheriting  from
       (until C++17)
	  std::iterator<std::input_iterator_tag, CharT,	Traits::off_type, /*
	  unspecified, usually CharT* */, CharT>.

Member functions
	  constructor		     constructs	a new istreambuf_iterator
				     (public member function)
	  destructor		     destructs an istreambuf_iterator
	  (implicitly declared)	     (public member function)
	  operator*		     obtains a copy of the current character
	  operator->		      accesses a member	of the current charac-
       ter, if CharT has
	  (since C++11)(until C++17) members
				     (public member function)
	  operator++		     advances the iterator
	  operator++(int)	     (public member function)
				     tests if  both  istreambuf_iterators  are
       end-of-stream or
	  equal			     if	both are valid
				     (public member function)

Non-member functions
	  operator==	     compares two istreambuf_iterators
	  operator!=	     (function template)
	  (removed in C++20)

Example
       // Run this code

	#include <string>
	#include <sstream>
	#include <iostream>
	#include <iterator>

	int main()
	{
	    //	typical	use case: an input stream represented as a pair	of it-
       erators
	    std::istringstream in{"Hello, world"};
	    std::istreambuf_iterator<char> it{in}, end;
	    std::string	ss{it, end};
	    std::cout << "ss has " << ss.size()	<< " bytes; "
			 "it holds \"" << ss <<	"\"\n";

	    // demonstration of	the single-pass	nature
	    std::istringstream s{"abc"};
	    std::istreambuf_iterator<char> i1{s}, i2{s};
	    std::cout << "i1 returns '"	<< *i1 << "'\n"
			 "i2 returns '"	<< *i2 << "'\n";
	    ++i1;
	    std::cout << "after	incrementing i1, but not i2\n"
			 "i1 returns '"	<< *i1 << "'\n"
			 "i2 returns '"	<< *i2 << "'\n";
	    ++i2;
	    std::cout << "after	incrementing i2, but not i1\n"
			 "i1 returns '"	<< *i1 << "'\n"
			 "i2 returns '"	<< *i2 << "'\n";
	}

Output:
	ss has 12 bytes; it holds "Hello, world"
	i1 returns 'a'
	i2 returns 'a'
	after incrementing i1, but not i2
	i1 returns 'b'
	i2 returns 'b'
	after incrementing i2, but not i1
	i1 returns 'c'
	i2 returns 'c'

See also
	  ostreambuf_iterator  output  iterator	 that	writes	 to   std::ba-
       sic_streambuf
			      (class template)
	  istream_iterator	input	iterator   that	 reads	from  std::ba-
       sic_istream
			      (class template)

http://cppreference.com		  2022.07.31	   std::istreambuf_iterator(3)

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