std::istreambuf_iterator

科技促进发展：司瑞安布夫[医]迭代器

Defined in header
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是一个单程输入迭代器，它从std::basic_streambuf对象，它是为其构造的。

默认构造std::istreambuf_iterator被称为流尾迭代器。当一个有效的std::istreambuf_iterator到达底层流的末尾，它就等于流结束迭代器.。解除引用或增量将进一步调用未定义的行为。

std::istreambuf_iterator有一个简单的复制构造函数、一个默认构造函数和一个简单的析构函数。

成员类型

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>

成员函数

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

非会员职能

operator==operator!=	compares two istreambuf_iterators (function template)

成员类型

Member type	Definition
value_type	CharT
difference_type	Traits::off_type
pointer	/* unspecified, usually CharT* */
reference	CharT
iterator_category	std::input_iterator_tag

注意：在C++17之前，这些成员类型必须通过从std::iterator<std::input_iterator_tag,CharT,Traits::off_type,/* unspecified, usually CharT* */,CharT>...

例

二次

#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';
 
}

二次

产出：

二次

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

二次

另见

ostreambuf_iterator	output iterator that writes to std::basic_streambuf (class template)
istream_iterator	input iterator that reads from std::basic_istream (class template)

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