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std::begin

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Revision as of 22:04, 31 May 2013 by P12bot (Talk | contribs)

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());
(1) (since C++11)
template< class T, size_t N >
T* begin( T (&array)[N] );
(2) (since C++11)
template< class C >
auto cbegin( const C& c ) -> decltype(std::begin(c));
(3) (since C++14)

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

1) Returns a possibly const-qualified iterator to the beginning of the container c.
2) Returns a pointer to the beginning of the array array.
3) Returns a const-qualified iterator to the beginning of the container c.

range-begin-end.svg

Contents

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:

specializes std::begin
(function template) [edit]
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

See also

(C++11)(C++14)
returns an iterator to the end of a container or array
(function) [edit]