Defined in header <iterator> | ||
|---|---|---|
template< class CharT, class Traits = std::char_traits<CharT> >
class istreambuf_iterator : public std::iterator< std::input_iterator_tag,
CharT,
typename Traits::off_type,
/* unspecified, usually CharT* */,
CharT >
| (until C++17) | |
template< class CharT, class Traits = std::char_traits<CharT> > class istreambuf_iterator; | (since C++17) |
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. Dereferencing or incrementing it further invokes undefined behavior.
std::istreambuf_iterator has a trivial copy constructor, a constexpr default constructor, and a trivial destructor.
| Member type | Definition |
|---|---|
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> |
| /* proxy */ | Implementation defined class type. The name proxy is for exposition only.A proxy object holds a char_type character and a streambuf_type* pointer.Deferencing a proxy object with operator* yields the stored character. |
constructs a new istreambuf_iterator (public member function) |
|
| (destructor)
(implicitly declared) | destructs an istreambuf_iterator (public member function) |
|
(since C++11)(until C++17) | obtains a copy of the current character accesses a member of the current character, if CharT has members (public member function) |
| advances the iterator (public member function) |
|
tests if both istreambuf_iterators are end-of-stream or if both are valid (public member function) |
compares two istreambuf_iterators (function template) |
| Member type | Definition |
|---|---|
value_type | CharT |
difference_type | Traits::off_type |
pointer | /* unspecified, usually CharT* */ |
reference | CharT |
iterator_category | std::input_iterator_tag |
| These member types are required to be obtained by inheriting from | (until C++17) |
#include <vector>
#include <sstream>
#include <iostream>
#include <iterator>
int main()
{
// typical use case: an input stream represented as a pair of iterators
std::istringstream in("Hello, world");
std::vector<char> v( (std::istreambuf_iterator<char>(in)),
std::istreambuf_iterator<char>() );
std::cout << "v has " << v.size() << " bytes. ";
v.push_back('\0');
std::cout << "it holds \"" << &v[0] << "\"\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; // this makes the apparent value of *i2 to jump from 'a' to 'c'
std::cout << "after incrementing i2, but not i1\n"
<< "i1 returns " << *i1 << '\n'
<< "i2 returns " << *i2 << '\n';
}Output:
v has 12 bytes. it holds "Hello, world" i1 returns a i2 returns a after incrementing i1, but not i2 i1 returns b i2 returns a after incrementing i2, but not i1 i1 returns b i2 returns c
output iterator that writes to std::basic_streambuf (class template) |
|
input iterator that reads from std::basic_istream (class template) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/iterator/istreambuf_iterator