std::begin

From cppreference.com
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.

Contents

[edit] Parameters

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

[edit] Return value

an iterator to the beginning of c or array

[edit] 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>.

[edit] 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:

specializes std::begin
(function template)
specializes std::begin
(function template)

[edit] Example

#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

[edit] See also

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