istreambuf_iterator

istreambuf_iteratorinput_iterator

• Data Type and Member Function Indexes
• Synopsis
• Description
• Interface
• Types
• Nested Class Proxy
• Constructors
• Member Operators
• Public Member Function
• Non Member Functions
• Examples
• See Also
• Standards Conformance

Data Types
char_type int_type istream_type streambuf_type	traits_type

Member Functions

equal() operator*() operator++() operator==()

#include <streambuf> 
template<class charT, class traits = char_traits<charT> >
class istreambuf_iterator
: public input_iterator

The template class istreambuf_iterator reads successive characters from the stream buffer for which it was constructed. operator* provides access to the current input character, if any, and operator++ advances to the next input character. If the end of stream is reached, the iterator becomes equal to the end of stream iterator value, which is constructed by the default constructor, istreambuf_iterator(). An istreambuf_iterator object can be used only for one-pass-algorithms.

template<class charT, class traits = char_traits<charT> >
class istreambuf_iterator
: public input_iterator {

 public:

  typedef charT                          char_type;
  typedef typename traits::int_type      int_type;
  typedef traits                         traits_type;
  typedef basic_streambuf<charT, traits> streambuf_type;
  typedef basic_istream<charT, traits>   istream_type;

  class proxy;  
  
  istreambuf_iterator() throw();
  istreambuf_iterator(istream_type& s)  throw();
  istreambuf_iterator(streambuf_type *s) throw();
  istreambuf_iterator(const proxy& p) throw();

  char_type operator*();
  istreambuf_iterator<charT, traits>& operator++();
  proxy operator++(int);
  bool equal(istreambuf_iterator<charT, traits>& b);

};

template<class charT, class traits>
bool operator==(istreambuf_iterator<charT, traits>& a,
                istreambuf_iterator<charT, traits>& b);

char_type

The type char_type is a synonym for the template parameter charT.

int_type

The type int_type is a synonym of type traits::in_type.

istream_type

The type istream_type is an instantiation of class basic_istream on types charT and traits:

typedef basic_istream<charT, traits> istream_type;

streambuf_type

The type streambuf_type is an instantiation of class basic_streambuf on types charT and traits:

typedef basic_streambuf<charT, traits> streambuf_type;

traits_type

The type traits_type is a synonym for the template parameter traits.

Class istreambuf_iterator<charT,traits>::proxy provides a temporary placeholder as the return value of the post-increment operator. It keeps the character pointed to by the previous value of the iterator for some possible future access.

istreambuf_iterator() 
  throw();

Constructs the end of stream iterator.

istreambuf_iterator(istream_type& s)
  throw();

Constructs an istreambuf_iterator that inputs characters using the basic_streambuf object pointed to by s.rdbuf(). If s.rdbuf() is a null pointer, the istreambuf_iterator is the end-of-stream iterator.

istreambuf_iterator(streambuf_type *s)
  throw();

Constructs an istreambuf_iterator that inputs characters using the basic_streambuf object pointed at by s. If s is a null pointer, the istreambuf_iterator is the end-of-stream iterator.

istreambuf_iterator(const proxy& p)
  throw();

Constructs an istreambuf_iterator that uses the basic_streambuf object embedded in the proxy object.

char_type 
operator*();

Returns the character pointed at by the input sequence of the attached stream buffer. If no character is available, the iterator becomes equal to the end-of-stream iterator.

istreambuf_iterator<charT, traits>& 
operator++();

Increments the input sequence of the attached stream buffer to point to the next character. If the current character is the last one, the iterator becomes equal to the end-of-stream iterator.

proxy 
operator++(int);

Increments the input sequence of the attached stream buffer to point to the next character. If the current character is the last one, the iterator becomes equal to the end-of-stream iterator. The proxy object returned contains the character pointed at before carrying out the post-increment operator.

bool 
equal(istreambuf_iterator<charT, traits>& b);

Returns true if and only if both iterators are at end of stream, or neither is at end of stream, regardless of what stream buffer object they are using.

template<class charT, class traits>
bool 
operator==(istreambuf_iterator<charT, traits>& a,
                istreambuf_iterator<charT, traits>& b);

Returns a.equal(b).

//
// stdlib/examples/manual/istreambuf_iterator.cpp
//
#include<iostream>
#include<fstream>

void main ( )
{
  using namespace std;

  // open the file is_iter.out for reading and writing
  ofstream out("is_iter.out", ios_base::out | ios_base::in );

  // output the example sentence into the file
  out << "Ceci est un simple example pour demontrer le" << endl;
  out << "fonctionement de istreambuf_iterator";

  // seek to the beginning of the file
  out.seekp(0);

  // construct an istreambuf_iterator pointing to
  // the ofstream object underlying stream buffer
  istreambuf_iterator<char> iter(out.rdbuf());

  // construct an end of stream iterator
  istreambuf_iterator<char> end_of_stream_iterator;

  cout << endl;

  // output the content of the file
  while( !iter.equal(end_of_stream_iterator) )

  // use both operator++ and operator*
  cout << *iter++;

  cout << endl;

}

basic_streambuf(3C++), basic_istream(3C++), ostreambuf_iterator(3C++)

Working Paper for Draft Proposed International Standard for Information Systems--Programming Language C++, Section 24.4.3

ANSI X3J16/ISO WG21 Joint C++ Committee

©Copyright 1996, Rogue Wave Software, Inc.