std::ostreambuf_iterator<CharT,Traits>::ostreambuf_iterator

 

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迭代器库

迭代器概念
indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) is-integer-like is-signed-integer-like (C++20)(C++20)	sentinel_for (C++20) sized_sentinel_for (C++20) input_iterator (C++20) output_iterator (C++20) input_or_output_iterator (C++20)	forward_iterator (C++20) bidirectional_iterator (C++20) random_access_iterator (C++20) contiguous_iterator (C++20)
迭代器原语
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20)	iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++23)(C++20)(C++20)	iterator (C++17 中弃用) iterator_traits incrementable_traits (C++20) indirectly_readable_traits (C++20)
算法概念与工具
间接可调用概念
indirectly_unary_invocableindirectly_regular_unary_invocable (C++20)(C++20)	indirect_unary_predicate (C++20) indirect_binary_predicate (C++20)	indirect_equivalence_relation (C++20) indirect_strict_weak_order (C++20)
常用算法要求
indirectly_movable (C++20) indirectly_movable_storable (C++20) indirectly_copyable (C++20)	indirectly_copyable_storable (C++20)   indirectly_swappable (C++20) indirectly_comparable (C++20)	permutable (C++20) mergeable (C++20) sortable (C++20)
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indirect_result_t (C++20)	projected (C++20)	projected_value_t (C++26)
迭代器适配器
reverse_iterator make_reverse_iterator (C++14) move_iterator (C++11) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20)	front_insert_iterator back_insert_iterator inserter insert_iterator front_inserter back_inserter move_sentinel (C++20)	common_iterator (C++20) counted_iterator (C++20) basic_const_iterator (C++23) const_iterator (C++23) const_sentinel (C++23) make_const_iterator (C++23) make_const_sentinel (C++23)
流迭代器 istream_iterator    ostream_iterator istreambuf_iterator ostreambuf_iterator	迭代器定制点 ranges::iter_move (C++20) ranges::iter_swap (C++20)
迭代器操作 advance distance prev (C++11)   next (C++11) ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)	范围访问 begincbegin (C++11)(C++14) rbegincrbegin (C++14)(C++14)   endcend (C++11)(C++14) rendcrend (C++14)(C++14)   sizessize (C++17)(C++20) empty (C++17) data (C++17)

 

std::ostreambuf_iterator

成员函数

ostreambuf_iterator::ostreambuf_iterator

ostreambuf_iterator::operator=

ostreambuf_iterator::operator*

ostreambuf_iterator::operator++ostreambuf_iterator::operator++(int)

ostreambuf_iterator::failed

 

	(1)
ostreambuf_iterator( streambuf_type* buffer ) throw();			(C++11 前)
ostreambuf_iterator( streambuf_type* buffer ) noexcept;			(C++11 起)
		(2)
ostreambuf_iterator( ostream_type& stream ) throw();				(C++11 前)
ostreambuf_iterator( ostream_type& stream ) noexcept;				(C++11 起)

1) 构造迭代器，将私有的 streambuf_type* 成员设为 buffer 并将 failed() 标志设为 false。buffer 是空指针时行为未定义。

2) 同 ostreambuf_iterator(stream.rdbuf())。

参数

stream	-	拥有的 rdbuf() 会被此迭代器访问的输出流
buffer	-	此迭代器要访问的输出流缓冲

示例

运行此代码

#include <fstream>
#include <iostream>
#include <iterator>
 
int main()
{
    const char* file = "test.txt";
    {
        std::basic_filebuf<char> f;
        f.open(file, std::ios::out);
        std::ostreambuf_iterator<char> out1(&f);
        *out1 = 'a'; // 通过迭代器写入文件
    }
 
    // 从文件读回
    char a;
    std::cout << ((std::ifstream{file} >> a), a) << std::endl;
 
    std::ostreambuf_iterator<wchar_t> out2{std::wcout};
    *out2 = L'b';
}

输出：

a
b

缺陷报告

下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。

缺陷报告	应用于	出版时的行为	正确行为
LWG 112	C++98	要求"实参不能为空"应用到了重载 (2)	改为应用到重载 (1)
P2325R3	C++20	因为 C++20 迭代器必须是 default_initializable 的而提供了默认构造函数	与该要求一同移除