Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.
NAME
istreambuf_iterator
- Reads successive characters from the stream buffer for
which it was constructed.
SYNOPSIS
#include <streambuf>
template<class charT, class traits = char_traits<charT> >
class istreambuf_iterator
: public input_iterator
DESCRIPTION
The template class_istreambuf_iterator reads successive
characters from the stream buffer for which it was con-
structed. operator* gives access to the current input char-
acter, 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.
INTERFACE
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);
template<class charT, class traits>
bool operator !=(istreambuf_iterator<charT, traits>& a,
istreambuf_iterator<charT, traits>& b);
TYPES
char_type
The type char_type is a synonym for the template parame-
ter 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 param-
eter traits.
NESTED CLASS PROXY
Class istreambuf_iterator<charT,traits>::proxy_is a tem-
porary placeholder for 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.
CONSTRUCTORS
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 to 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.
MEMBER OPERATORS
char_type
operator*();
Returns the character pointed to 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 to before carrying out the
post-increment operator.
PUBLIC MEMBER FUNCTIONS
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.
NON-MEMBER FUNCTIONS
template<class charT, class traits>
bool
operator==(istreambuf_iterator<charT, traits>& a,
istreambuf_iterator<charT, traits>& b);
Returns a.equal(b).
template<class charT, class traits>
bool
operator==(istreambuf_iterator<charT, traits>& a,
istreambuf_iterator<charT, traits>& b);
Returns !(a.equal(b)).
EXAMPLE
//
// 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;
}
SEE ALSO
basic_streambuf(3C++), basic_istream(3C++),
ostreambuf_iterator(3C++)
Working Paper for Draft Proposed International Standard for
Information Systems--Programming Language C++, Section
24.5.3
STANDARDS CONFORMANCE
ANSI X3J16/ISO WG21 Joint C++ Committee