operator-(std::reverse_iterator)

 

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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)
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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 (在 C++17 中已弃用) iterator_traits incrementable_traits (C++20) indirectly_readable_traits (C++20)
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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)
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indirect_result_t (C++20)	projected (C++20)	projected_value_t (C++26)
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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)
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std::reverse_iterator

成员函数

reverse_iterator::reverse_iterator

reverse_iterator::operator=

reverse_iterator::base

reverse_iterator::operator*reverse_iterator::operator->

reverse_iterator::operator[]

reverse_iterator::operator++reverse_iterator::operator+reverse_iterator::operator+=reverse_iterator::operator--reverse_iterator::operator-reverse_iterator::operator-=

非成员函数

operator==operator!=operator<operator<=operator>operator>=operator<=> (C++20)

operator+

operator-

iter_move (C++20)

iter_swap (C++20)

make_reverse_iterator (C++14)

 

定义于头文件 <iterator>
template< class Iter1, class Iter2 > typename reverse_iterator<Iter>::difference_type     operator-( const reverse_iterator<Iter1>& lhs,                const reverse_iterator<Iter2>& rhs );		(直到 C++11)
template< class Iter1, class Iter2 > auto operator-( const reverse_iterator<Iter1>& lhs,                 const reverse_iterator<Iter2>& rhs )     -> decltype(rhs.base() - lhs.base());		(自 C++11 起) (constexpr 自 C++17 起)

返回两个迭代器适配器之间的距离。

参数

lhs, rhs

-

用于计算差值的迭代器适配器

返回值

rhs.base() - lhs.base()

注解

operator- 返回 rhs.base() - lhs.base() 而不是 lhs.base() - rhs.base()，因为这是一个逆向迭代器。

示例

运行此代码

#include <iostream>
#include <iterator>
#include <list>
#include <vector>
 
int main()
{
    std::vector vec{0, 1, 2, 3};
    std::reverse_iterator<std::vector<int>::iterator>
        vec_ri1{std::reverse_iterator{vec.rbegin()}},
        vec_ri2{std::reverse_iterator{vec.rend()}};
    std::cout << (vec_ri2 - vec_ri1) << ' '; // 4
    std::cout << (vec_ri1 - vec_ri2) << '\n'; // -4
 
    std::list lst{5, 6, 7, 8};
    std::reverse_iterator<std::list<int>::iterator>
        lst_ri1{std::reverse_iterator{lst.rbegin()}},
        lst_ri2{std::reverse_iterator{lst.rend()}};
//  auto n = (lst_ri1 - lst_ri2); // Error: the underlying iterators do not
                                  //        model random access iterator
}

输出

4 -4

缺陷报告

以下行为变更缺陷报告被追溯应用到先前发布的 C++ 标准。

DR	应用于	已发布行为	正确行为
LWG 280	C++98	不允许异构减法	允许

参见

operator++operator++(int)operator+=operator+operator--operator--(int)operator-=operator-	递增或递减 reverse_iterator (公共成员函数)
operator+	递增迭代器 (函数模板)