std::begin

 

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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 C > auto begin( C& c ) -> decltype(c.begin());	(1)	（C++11 起）
template< class C > auto begin( const C& c ) -> decltype(c.begin());	(2)	（C++11 起）
template< class T, size_t N > T* begin( T (&array)[N] );	(3)	（C++11 起）

c或数组给定的容器array返回一个迭代的开始.

Original:

Returns an iterator to the beginning of the given container c or array array.

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参数

c	-	的容器具有begin方法 Original: a container with a begin method The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
array	-	任意类型的数组 Original: an array of arbitrary type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

返回值

c或array一个迭代的开始

Original:

an iterator to the beginning of c or array

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注释

除了被包括在<iterator>std::begin保证变得可用，如果没有下面的接头连接器包括：<array>，<deque>，<forward_list>，<list>，<map>，<regex>，<set>，<string>，<unordered_map>，<unordered_set>，并<vector>.

Original:

In addition to being included in <iterator>, std::begin is guaranteed to become available if any of the following headers are included: <array>, <deque>, <forward_list>, <list>, <map>, <regex>, <set>, <string>, <unordered_map>, <unordered_set>, and <vector>.

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专业化

定制专业的std::begin可能会不露出一个合适的begin()成员函数的类，还可以迭代。以下专业的标准库已经提供了

Original:

Custom specializations of std::begin may be provided for classes that do not expose a suitable begin() member function, yet can be iterated. The following specializations are already provided by the standard library:

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std::begin(std::initializer_list) （C++11）	专业std::begin Original: specializes std::begin The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板）
std::begin(std::valarray) （C++11）	专业std::begin Original: specializes std::begin The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板）

为例

#include <iostream>
#include <vector>
#include <iterator>
 
int main() 
{
    std::vector<int> v = { 3, 1, 4 };
    auto vi = std::begin(v);
    std::cout << *vi << '\n'; 
 
    int a[] = { -5, 10, 15 };
    auto ai = std::begin(a);
    std::cout << *ai << '\n';
}

Output:

3
-5

另请参阅

end （C++11）	返回一个迭代器的容器或数组 Original: returns an iterator to the end of a container or array The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数）