Library: Iterators
istreambuf_iteratorinput_iterator
|
char_type equal() int_type |
istreambuf_iterator() istream_type operator*() |
operator++() streambuf_type traits_type |
Iterator that reads successive characters from the stream buffer for which it was constructed
#include <streambuf>
namespace std {
template<class charT, class traits = char_traits<charT> >
class istreambuf_iterator;
}
The class template istreambuf_iterator reads successive characters from the stream buffer for which it was constructed. operator*() gives 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.
namespace std {
template<class charT, class traits = char_traits<charT> >
class istreambuf_iterator
: public iterator<input_iterator_tag, charT, typename
traits::off_type, charT*, charT&>
{
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*() const;
istreambuf_iterator& operator++();
proxy operator++(int);
bool equal(istreambuf_iterator& b) const;
};
template<class charT, class traits>
bool operator==(const istreambuf_iterator<charT, traits>& a,
const istreambuf_iterator<charT, traits>& b);
template<class charT, class traits>
bool operator!=(const istreambuf_iterator<charT, traits>& a,
const 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_type::int_type.
istream_type
The type istream_type is a synonym of type basic_istream<char_type, traits_type>.
typedef basic_istream<charT, traits> istream_type;
streambuf_type
The type streambuf_type is a synonym of type basic_streambuf<char_type, traits_type>.
traits_type
The type traits_type is a synonym for the template parameter traits.
Class istreambuf_iterator<charT,traits>::proxy is a temporary 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.
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.
char_type operator*() const;
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& 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.
bool equal(istreambuf_iterator& b) const;
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==(const istreambuf_iterator<charT, traits>& a,
const istreambuf_iterator<charT, traits>& b);
Returns a.equal(b).
template<class charT, class traits>
bool
operator!=(const istreambuf_iterator<charT, traits>& a,
const istreambuf_iterator<charT, traits>& b);
Returns !(a.equal(b)).
//
// istreambuf_iterator.cpp
//
#include <iostream> // for cout, endl
#include <fstream> // for ofstream, istreambuf_iterator
#include <stdio.h> // for tmpnam () and remove ()
int main ( )
{
// create a temporary filename
const char *fname = tmpnam (0);
if (!fname)
return 1;
// open the file is_iter.out for reading and writing
std::ofstream out (fname, std::ios::out | std::ios::in |
std::ios::trunc);
// output the example sentence into the file
out << "Ceci est un simple exemple pour démontrer le\n"
"fonctionnement de istreambuf_iterator.";
// seek to the beginning of the file
out.seekp (0);
// construct an istreambuf_iterator pointing to
// the ofstream object underlying streambuffer
std::istreambuf_iterator<char, std::char_traits<char> >
iter (out.rdbuf ());
// construct an end of stream iterator
const std::istreambuf_iterator<char,
std::char_traits<char> > end;
std::cout << std::endl;
// output the content of the file
while (!iter.equal (end)) {
// use both operator++ and operator*
std::cout << *iter++;
}
std::cout << std::endl;
// remove temporary file
remove (fname);
return 0;
}
Program Output:
Ceci est un simple exemple pour démontrer le
fonctionnement de istreambuf_iterator.
basic_streambuf, basic_istream, ostreambuf_iterator
ISO/IEC 14882:1998 -- International Standard for Information Systems --Programming Language C++, Section 24.5.3