std::distance

 

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迭代器库

迭代器原语 Original: Iterator primitives The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
iterator_traits
input_iterator_tag output_iterator_tag forward_iterator_tag bidirectional_iterator_tag random_access_iterator_tag
iterator
迭代器适配器 Original: Iterator adaptors The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
reverse_iterator
move_iterator （C++11） back_insert_iterator front_insert_iterator insert_iterator	make_move_iterator （C++11） back_inserter front_inserter inserter
流迭代器 Original: Stream iterators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
istream_iterator
ostream_iterator
istreambuf_iterator
ostreambuf_iterator
迭代器操作 Original: Iterator operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
advance
distance
prev （C++11）
next （C++11）
远程接入 Original: Range access The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
begin （C++11）
end （C++11）

 

Defined in header <iterator>
template< class InputIt > typename std::iterator_traits<InputIt>::difference_type     distance( InputIt first, InputIt last );

返回的元素数之间first和last.

Original:

Returns the number of elements between first and last.

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的行为是不确定的，如果last是不可达的，从first可能反复递增first.

Original:

The behavior is undefined if last is not reachable from first by (possibly repeatedly) incrementing first.

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参数

first	-	迭代器，指向第一个元素 Original: iterator pointing to the first element The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
last	-	迭代器，指向的最后一个元素 Original: iterator pointing to the last element The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Type requirements
- InputIt must meet the requirements of InputIterator. The operation is more efficient if InputIt additionally meets the requirements of RandomAccessIterator

返回值

的数量之间first和last的元素，

Original:

The number of elements between first and last.

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复杂性

线性.

Original:

Linear.

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然而，如果InputIt附加RandomAccessIterator符合要求的，复杂度为恒定

Original:

However, if InputIt additionally meets the requirements of RandomAccessIterator, complexity is constant.

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为例

#include <iostream>
#include <iterator>
#include <vector>
 
int main() 
{
    std::vector<int> v{ 3, 1, 4 };
 
    auto distance = std::distance(v.begin(), v.end());
 
    std::cout << distance << '\n';
}

Output:

3

另请参阅

advance	给定距离的迭代器 Original: advances an iterator by given distance The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数）