通过

reverse_iterator 类

  • 项目

此类模板是迭代器适配器，描述在行为上与随机访问迭代器或双向迭代器类似（只不过方向相反）的反向迭代器对象。 它允许向后遍历范围。

语法

template <class RandomIterator>
class reverse_iterator

参数

RandomIterator 一种类型，此类型表示要进行适配化以反向操作的迭代器。

备注

现有 C++ 标准库容器还定义 reverse_iterator 和 const_reverse_iterator 类型，并拥有返回反向迭代器的成员函数 rbegin 和 rend。 这些迭代器具有覆盖语义。 reverse_iterator 适配器在提供插入语义时补充此功能，还可与流一起使用。

需要双向迭代器的 reverse_iterator 不能调用 operator+=、operator+、operator-=、operator- 或 operator[] 中的任何成员函数，这些成员函数只能与随机访问迭代器一起使用。

如果迭代器范围为 [first, last)，其中左侧的方括号指示包含 first，右侧的括号指示包含到 last 的元素，但不包含 last 本身。 相同元素包含在反向序列 [ rev - first, rev - last) 中，这样，如果 last 是序列中的超出末尾元素，则反向序列中的第一个元素rev - first 指向 *(last - 1)。 将所有反向迭代器与其基础迭代器关联的标识是：

&*(reverse_iterator (i)) == &*(i - 1).

在实际操作中，这意味着在反向序列中，reverse_iterator 将引用迭代器在原有序列中引用的元素之外（右侧）一个位置的元素。 因此，如果迭代器在序列 (2, 4, 6, 8) 中发现元素 6，则 reverse_iterator 将在反向序列 (8, 6, 4, 2) 中发现元素 4。

构造函数

构造函数 说明
reverse_iterator 构造默认 reverse_iterator 或从基础迭代器构造 reverse_iterator。

Typedef

类型名称 说明
difference_type 一种类型，此类型提供引用同一容器中的元素的两个 reverse_iterator 之间的差异。
iterator_type 一种类型，此类型为 reverse_iterator 提供基础迭代器。
pointer 一种类型，此类型提供指向 reverse_iterator 所发现元素的指针。
reference 一种类型，此类型提供对 reverse_iterator 所发现元素的引用。

成员函数

成员函数 说明
base 将基础迭代器从其 reverse_iterator 恢复。

运算符

运算符 说明
operator_star 返回 reverse_iterator 发现的元素。
operator+ 将偏移量添加到迭代器，并返回在新偏移位置处发现插入元素的新 reverse_iterator。
operator++ 将 reverse_iterator 递增到下一元素。
operator+= 从 reverse_iterator 添加指定偏移量。
operator- 从 reverse_iterator 减去偏移量，并返回在偏移位置处发现元素的 reverse_iterator。
operator-- 将 reverse_iterator 递减到前一元素。
operator-= 从 reverse_iterator 减去指定偏移量。
operator-> 返回指向 reverse_iterator 发现的元素的指针。
operator[] 返回对于从 reverse_iterator 发现的元素偏移指定个位置的元素的引用。

要求

标头：<iterator>

命名空间： std

reverse_iterator::base

将基础迭代器从其 reverse_iterator 恢复。

RandomIterator base() const;

返回值

构成 reverse_iterator 的基础的迭代器。

注解

将所有反向迭代器与其基础迭代器关联的标识是：

&*(reverse_iterator (i)) == &*(i - 1).

在实际操作中，这意味着在反向序列中，reverse_iterator 将引用迭代器在原有序列中引用的元素之外（右侧）一个位置的元素。 因此，如果迭代器在序列 (2, 4, 6, 8) 中发现元素 6，则 reverse_iterator 将在反向序列 (8, 6, 4, 2) 中发现元素 4。

示例

// reverse_iterator_base.cpp
// compile with: /EHsc
#include <iterator>
#include <algorithm>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for ( i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 2 * i );
   }

   vector <int>::iterator vIter;
   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin ( ) ; vIter != vec.end ( ); vIter++ )
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   vector <int>::iterator pos, bpos;
   pos = find ( vec.begin ( ), vec.end ( ), 6 );
   cout << "The iterator pos points to: " << *pos << "." << endl;

   typedef reverse_iterator<vector<int>::iterator>::iterator_type it_vec_int_type;

   reverse_iterator<it_vec_int_type> rpos ( pos );
   cout << "The reverse_iterator rpos points to: " << *rpos
        << "." << endl;

   bpos = rpos.base ( );
   cout << "The iterator underlying rpos is bpos & it points to: "
        << *bpos << "." << endl;
}

reverse_iterator::difference_type

一种类型，此类型提供引用同一容器中的元素的两个 reverse_iterator 之间的差异。

typedef typename iterator_traits<RandomIterator>::difference_type  difference_type;

备注

reverse_iterator 差异类型与迭代器差异类型相同。

该类型为迭代器特征类型名 iterator_traits<RandomIterator>::pointer 的同义词。

示例

有关如何声明和使用 difference_type 的示例，请参阅 reverse_iterator::operator[]。

reverse_iterator::iterator_type

一种类型，此类型为 reverse_iterator 提供基础迭代器。

typedef RandomIterator iterator_type;

备注

该类型是模板参数 Iterator 的同义词。

示例

请参阅 reverse_iterator::base，获取关于如何声明和使用 iterator_type 的示例。

reverse_iterator::operator*

返回由 reverse_iterator 寻址的元素。

reference operator*() const;

返回值

由 reverse_iterator 寻址的元素的值。

备注

运算符返回 *( current - 1)。

示例

// reverse_iterator_op_ref.cpp
// compile with: /EHsc
#include <iterator>
#include <algorithm>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for (i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 2 * i );
   }

   vector <int>::iterator vIter;
   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin ( ) ; vIter != vec.end ( ); vIter++ )
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   vector <int>::iterator pos, bpos;
   pos = find ( vec.begin ( ), vec.end ( ), 6 );

   // Declare a difference type for a parameter
   // declare a reference return type
   reverse_iterator<vector<int>::iterator>::reference refpos = *pos;
   cout << "The iterator pos points to: " << refpos << "." << endl;
}

reverse_iterator::operator+

将偏移量添加到迭代器，并返回在新偏移位置处发现插入元素的新 reverse_iterator。

reverse_iterator<RandomIterator> operator+(difference_type Off) const;

参数

关闭
要添加到反向迭代器的偏移量。

返回值

寻址偏移元素的 reverse_iterator。

注解

仅当 reverse_iterator 满足随机访问迭代器的要求时才能使用此成员函数。

示例

// reverse_iterator_op_add.cpp
// compile with: /EHsc
#include <iterator>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for (i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 2 * i );
   }

   vector <int>::iterator vIter;
   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin( ) ; vIter != vec.end( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   // Initializing reverse_iterators to the first element
   vector <int>::reverse_iterator rVPOS1 = vec.rbegin ( );

   cout << "The iterator rVPOS1 initially points to the first "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;

   vector <int>::reverse_iterator rVPOS2 =rVPOS1 + 2; // offset added
   cout << "After the +2 offset, the iterator rVPOS2 points\n"
        << " to the 3rd element in the reversed sequence: "
        << *rVPOS2 << "." << endl;
}

The vector vec is: ( 2 4 6 8 10 ).
The vector vec reversed is: ( 10 8 6 4 2 ).
The iterator rVPOS1 initially points to the first element
in the reversed sequence: 10.
After the +2 offset, the iterator rVPOS2 points
to the 3rd element in the reversed sequence: 6.

reverse_iterator::operator++

向上一个元素逐量添加 reverse_iterato。

reverse_iterator<RandomIterator>& operator++();
reverse_iterator<RandomIterator> operator++(int);

返回值

第一个运算符返回前置递增的 reverse_iterator，而第二个运算符为后置递增运算符，返回递增的 reverse_iterator 的副本。

注解

仅当 reverse_iterator 满足双向迭代器的要求时才能使用此成员函数。

示例

// reverse_iterator_op_incr.cpp
// compile with: /EHsc
#include <iterator>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for ( i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 2 * i - 1 );
   }

   vector <int>::iterator vIter;
   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin( ) ; vIter != vec.end( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   // Initializing reverse_iterators to the last element
   vector <int>::reverse_iterator rVPOS1 = vec.rbegin( );

   cout << "The iterator rVPOS1 initially points to the first "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;

   rVPOS1++;  // postincrement, preincrement: ++rVPSO1

   cout << "After incrementing, the iterator rVPOS1 points\n"
        << " to the second element in the reversed sequence: "
        << *rVPOS1 << "." << endl;
}

The vector vec is: ( 1 3 5 7 9 ).
The vector vec reversed is: ( 9 7 5 3 1 ).
The iterator rVPOS1 initially points to the first element
in the reversed sequence: 9.
After incrementing, the iterator rVPOS1 points
to the second element in the reversed sequence: 7.

reverse_iterator::operator+=

从 reverse_iterator 添加指定偏移量。

reverse_iterator<RandomIterator>& operator+=(difference_type Off);

参数

关闭
迭代器要递增的偏移量。

返回值

由 reverse_iterator 寻址的元素的引用。

示例

// reverse_iterator_op_addoff.cpp
// compile with: /EHsc
#include <iterator>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for (i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 2 * i );
   }

   vector <int>::iterator vIter;

   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin( ) ; vIter != vec.end( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   // Initializing reverse_iterators to the last element
   vector <int>::reverse_iterator rVPOS1 = vec.rbegin ( );

   cout << "The iterator rVPOS1 initially points to the first "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;

   rVPOS1+=2;   // addition of an offset
   cout << "After the +2 offset, the iterator rVPOS1 now points\n"
        << " to the third element in the reversed sequence: "
        << *rVPOS1 << "." << endl;
}

The vector vec is: ( 2 4 6 8 10 ).
The vector vec reversed is: ( 10 8 6 4 2 ).
The iterator rVPOS1 initially points to the first element
in the reversed sequence: 10.
After the +2 offset, the iterator rVPOS1 now points
to the third element in the reversed sequence: 6.

reverse_iterator::operator-

从 reverse_iterator 减去偏移量，并返回在偏移位置处发现元素的 reverse_iterator。

reverse_iterator<RandomIterator> operator-(difference_type Off) const;

参数

关闭
要从 everse_iterator 中减去的偏移量。

返回值

寻址偏移元素的 reverse_iterator。

注解

仅当 reverse_iterator 满足随机访问迭代器的要求时才能使用此成员函数。

示例

// reverse_iterator_op_sub.cpp
// compile with: /EHsc
#include <iterator>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for ( i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 3 * i );
   }

   vector <int>::iterator vIter;

   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin( ) ; vIter != vec.end( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   // Initializing reverse_iterators to the first element
   vector <int>::reverse_iterator rVPOS1 = vec.rend ( ) - 1;

   cout << "The iterator rVPOS1 initially points to the last "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;

   vector <int>::reverse_iterator rVPOS2 =rVPOS1 - 2; // offset subtracted
   cout << "After the -2 offset, the iterator rVPOS2 points\n"
        << " to the 2nd element from the last in the reversed sequence: "
        << *rVPOS2 << "." << endl;
}

The vector vec is: ( 3 6 9 12 15 ).
The vector vec reversed is: ( 15 12 9 6 3 ).
The iterator rVPOS1 initially points to the last element
in the reversed sequence: 3.
After the -2 offset, the iterator rVPOS2 points
to the 2nd element from the last in the reversed sequence: 9.

reverse_iterator::operator--

向上一个元素逐量递减 reverse_iterato。

reverse_iterator<RandomIterator>& operator--();
reverse_iterator<RandomIterator> operator--(int);

返回值

第一个运算符返回前置递减的 reverse_iterator，而第二个运算符为后置递减运算符，返回递减的 reverse_iterator 的副本。

备注

仅当 reverse_iterator 满足双向迭代器的要求时才能使用此成员函数。

示例

// reverse_iterator_op_decr.cpp
// compile with: /EHsc
#include <iterator>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for (i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 2 * i - 1 );
   }

   vector <int>::iterator vIter;

   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin( ) ; vIter != vec.end( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   // Initializing reverse_iterators to the first element
   vector <int>::reverse_iterator rVPOS1 = vec.rend ( ) - 1;

   cout << "The iterator rVPOS1 initially points to the last "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;
   rVPOS1--;  // postdecrement, predecrement: --rVPSO1

   cout << "After the decrement, the iterator rVPOS1 points\n"
        << " to the next-to-last element in the reversed sequence: "
        << *rVPOS1 << "." << endl;
}

The vector vec is: ( 1 3 5 7 9 ).
The vector vec reversed is: ( 9 7 5 3 1 ).
The iterator rVPOS1 initially points to the last element
in the reversed sequence: 1.
After the decrement, the iterator rVPOS1 points
to the next-to-last element in the reversed sequence: 3.

reverse_iterator::operator-=

从 reverse_iterator 减去指定偏移量。

reverse_iterator<RandomIterator>& operator-=(difference_type Off);

参数

关闭
要从 reverse_iterator 中减去的偏移量。

备注

仅当 reverse_iterator 满足随机访问迭代器的要求时才能使用此成员函数。

运算符评估 current + Off，然后返回 *this。

示例

// reverse_iterator_op_suboff.cpp
// compile with: /EHsc
#include <iterator>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for (i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 3 * i );
   }

   vector <int>::iterator vIter;

   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin( ) ; vIter != vec.end( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   // Initializing reverse_iterators to the first element
   vector <int>::reverse_iterator rVPOS1 = vec.rend ( ) - 1;

   cout << "The iterator rVPOS1 initially points to the last "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;

   rVPOS1-=2;      // Subtraction of an offset
   cout << "After the -2 offset, the iterator rVPOS1 now points\n"
        << " to the 2nd element from the last in the reversed sequence: "
        << *rVPOS1 << "." << endl;
}

The vector vec is: ( 3 6 9 12 15 ).
The vector vec reversed is: ( 15 12 9 6 3 ).
The iterator rVPOS1 initially points to the last element
in the reversed sequence: 3.
After the -2 offset, the iterator rVPOS1 now points
to the 2nd element from the last in the reversed sequence: 9.

reverse_iterator::operator->

返回指向 reverse_iterator 发现的元素的指针。

pointer operator->() const;

返回值

指向由 reverse_iterator 寻址的元素的指针。

备注

运算符返回 &**this。

示例

// reverse_iterator_ptrto.cpp
// compile with: /EHsc
#include <iterator>
#include <algorithm>
#include <vector>
#include <utility>
#include <iostream>

int main( )
{
   using namespace std;

   typedef vector<pair<int,int> > pVector;
   pVector vec;
   vec.push_back(pVector::value_type(1,2));
   vec.push_back(pVector::value_type(3,4));
   vec.push_back(pVector::value_type(5,6));

   pVector::iterator pvIter;
   cout << "The vector vec of integer pairs is:\n( ";
   for ( pvIter = vec.begin ( ) ; pvIter != vec.end ( ); pvIter++)
      cout << "( " << pvIter -> first << ", " << pvIter -> second << ") ";
   cout << ")" << endl << endl;

   pVector::reverse_iterator rpvIter;
   cout << "The vector vec reversed is:\n( ";
   for ( rpvIter = vec.rbegin( ) ; rpvIter != vec.rend( ); rpvIter++ )
      cout << "( " << rpvIter -> first << ", " << rpvIter -> second << ") ";
   cout << ")" << endl << endl;

   pVector::iterator pos = vec.begin ( );
   pos++;
   cout << "The iterator pos points to:\n( " << pos -> first << ", "
   << pos -> second << " )" << endl << endl;

   pVector::reverse_iterator rpos (pos);

   // Use operator -> with return type: why type int and not int*
   int fint = rpos -> first;
   int sint = rpos -> second;

   cout << "The reverse_iterator rpos points to:\n( " << fint << ", "
   << sint << " )" << endl;
}

The vector vec of integer pairs is:
( ( 1, 2) ( 3, 4) ( 5, 6) )

The vector vec reversed is:
( ( 5, 6) ( 3, 4) ( 1, 2) )

The iterator pos points to:
( 3, 4 )

The reverse_iterator rpos points to:
( 1, 2 )

reverse_iterator::operator[]

返回对于从 reverse_iterator 发现的元素偏移指定个位置的元素的引用。

reference operator[](difference_type Off) const;

参数

关闭
reverse_iterator 地址的偏移量。

返回值

对元素偏移量的引用。

备注

运算符返回 *( *this + Off)。

示例

// reverse_iterator_ret_ref.cpp
// compile with: /EHsc
#include <iterator>
#include <algorithm>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for (i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 2 * i );
   }

   vector <int>::iterator vIter;
   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin ( ) ; vIter != vec.end ( ); vIter++ )
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   vector <int>::iterator pos;
   pos = find ( vec.begin ( ), vec.end ( ), 8 );
   reverse_iterator<vector<int>::iterator> rpos ( pos );

   // Declare a difference type for a parameter
   reverse_iterator<vector<int>::iterator>::difference_type diff = 2;

   cout << "The iterator pos points to: " << *pos << "." << endl;
   cout << "The iterator rpos points to: " << *rpos << "." << endl;

   // Declare a reference return type & use operator[]
   reverse_iterator<vector<int>::iterator>::reference refrpos = rpos [diff];
   cout << "The iterator rpos now points to: " << refrpos << "." << endl;
}

The vector vec is: ( 2 4 6 8 10 ).
The vector vec reversed is: ( 10 8 6 4 2 ).
The iterator pos points to: 8.
The iterator rpos points to: 6.
The iterator rpos now points to: 2.

reverse_iterator::pointer

一种类型，此类型提供指向 reverse_iterator 所发现元素的指针。

typedef typename iterator_traits<RandomIterator>::pointer pointer;

备注

该类型为迭代器特征类型名 iterator_traits<RandomIterator>::pointer 的同义词。

示例

// reverse_iterator_pointer.cpp
// compile with: /EHsc
#include <iterator>
#include <algorithm>
#include <vector>
#include <utility>
#include <iostream>

int main( )
{
   using namespace std;

   typedef vector<pair<int,int> > pVector;
   pVector vec;
   vec.push_back( pVector::value_type( 1,2 ) );
   vec.push_back( pVector::value_type( 3,4 ) );
   vec.push_back( pVector::value_type( 5,6 ) );

   pVector::iterator pvIter;
   cout << "The vector vec of integer pairs is:\n" << "( ";
   for ( pvIter = vec.begin ( ) ; pvIter != vec.end ( ); pvIter++)
      cout << "( " << pvIter -> first << ", " << pvIter -> second << ") ";
   cout << ")" << endl;

   pVector::reverse_iterator rpvIter;
   cout << "\nThe vector vec reversed is:\n" << "( ";
   for ( rpvIter = vec.rbegin( ) ; rpvIter != vec.rend( ); rpvIter++)
      cout << "( " << rpvIter -> first << ", " << rpvIter -> second << ") ";
   cout << ")" << endl;

   pVector::iterator pos = vec.begin ( );
   pos++;
   cout << "\nThe iterator pos points to:\n"
        << "( " << pos -> first << ", "
        << pos -> second << " )" << endl;

   pVector::reverse_iterator rpos (pos);
   cout << "\nThe iterator rpos points to:\n"
        << "( " << rpos -> first << ", "
        << rpos -> second << " )" << endl;
}

The vector vec of integer pairs is:
( ( 1, 2) ( 3, 4) ( 5, 6) )

The vector vec reversed is:
( ( 5, 6) ( 3, 4) ( 1, 2) )

The iterator pos points to:
( 3, 4 )

The iterator rpos points to:
( 1, 2 )

reverse_iterator::reference

一种类型，此类型提供对 reverse_iterator 所发现元素的引用。

typedef typename iterator_traits<RandomIterator>::reference reference;

备注

该类型是迭代器特征类型名 iterator_traits<RandomIterator>::reference 的同义词。

示例

有关如何声明和使用 reference 的示例，请参阅 reverse_iterator::operator[] 或 reverse_iterator::operator*。

reverse_iterator::reverse_iterator

构造默认 reverse_iterator 或从基础迭代器构造 reverse_iterator。

reverse_iterator();
explicit reverse_iterator(RandomIterator right);

template <class Type>
reverse_iterator(const reverse_iterator<Type>& right);

参数

right
适用于 reverse_iterator 的迭代器。

返回值

默认的 reverse_iterator 或用于调整基础迭代器的 reverse_iterator。

注解

将所有反向迭代器与其基础迭代器关联的标识是：

&*(reverse_iterator (i)) == &*(i-1)。

在实际操作中，这意味着在反向序列中，reverse_iterator 将引用迭代器在原有序列中引用的元素之外（右侧）一个位置的元素。 因此，如果迭代器在序列 (2, 4, 6, 8) 中发现元素 6，则 reverse_iterator 将在反向序列 (8, 6, 4, 2) 中发现元素 4。

示例

// reverse_iterator_reverse_iterator.cpp
// compile with: /EHsc
#include <iterator>
#include <algorithm>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for ( i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( i );
   }

   vector <int>::iterator vIter;
   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin ( ) ; vIter != vec.end ( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   vector <int>::iterator pos;
   pos = find ( vec.begin ( ), vec.end ( ), 4 );
   cout << "The iterator pos = " << *pos << "." << endl;

   vector <int>::reverse_iterator rpos ( pos );
   cout << "The reverse_iterator rpos = " << *rpos
        << "." << endl;
}

另请参阅

<iterator>
C++ 标准库中的线程安全
C++ 标准库参考