std::begin

 

C++

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Regular expressions library (C++11)

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Thread support library (C++11)

 

Iterator library

Iterator primitives
iterator_traits
input_iterator_tag output_iterator_tag forward_iterator_tag bidirectional_iterator_tag random_access_iterator_tag
iterator
Iterator adaptors
reverse_iterator
move_iterator (C++11) back_insert_iterator front_insert_iterator insert_iterator	make_move_iterator (C++11) back_inserter front_inserter inserter
Stream iterators
istream_iterator
ostream_iterator
istreambuf_iterator
ostreambuf_iterator
Iterator operations
advance
distance
prev (C++11)
next (C++11)
Range access
begin (C++11)
end (C++11)

 

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

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

Parameters

c	-	a container with a begin method
array	-	an array of arbitrary type

Return value

an iterator to the beginning of c or array

Notes

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>.

Specializations

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:

std::begin(std::initializer_list) (C++11)	specializes std::begin (function template)
std::begin(std::valarray) (C++11)	specializes std::begin (function template)

Example

run this code

#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

See also

end (C++11)	returns an iterator to the end of a container or array (function)