Information
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

begin

Retrieves an iterator to the first element in a specified container.

template<class Container>
    auto begin(Container& cont)
        -> decltype(cont.begin());
template<class Container>
    auto begin(const Container& cont) 
        -> decltype(cont.begin());
template<class Ty, class Size>
    Ty *begin(Ty (&array)[Size]);

cont

A container.

array

An array of objects of type Ty.

The first two template functions return cont.begin(). The first function is non-constant; the second one is constant.

The third template function returns array.

We recommend that you use this template function in place of container member begin() when more generic behavior is required.

// cl.exe /EHsc /nologo /W4 /MTd 
#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <vector>

template <typename C> void reverse_sort(C& c) {
    using std::begin;
    using std::end;

    std::sort(begin(c), end(c), std::greater<>());
}

template <typename C> void print(const C& c) {
    for (const auto& e : c) {
        std::cout << e << " ";
    }

    std::cout << "\n";
}

int main() {
    std::vector<int> v = { 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1 };

    print(v);
    reverse_sort(v);
    print(v);

    std::cout << "--\n";

    int arr[] = { 23, 70, 35, 106, 53, 160, 80, 40, 20, 10, 5, 16, 8, 4, 2, 1 };

    print(arr);
    reverse_sort(arr);
    print(arr);
}
Output:
11 34 17 52 26 13 40 20 10 5 16 8 4 2 1
52 40 34 26 20 17 16 13 11 10 8 5 4 2 1
--
23 70 35 106 53 160 80 40 20 10 5 16 8 4 2 1
160 106 80 70 53 40 35 23 20 16 10 8 5 4 2 1

The function reverse_sort supports containers of any kind, in addition to regular arrays, because it calls the non-member version of begin(). If reverse_sort were coded to use the container member begin():

template <typename C> void reverse_sort(C& c) {
    using std::begin;
    using std::end;

    std::sort(c.begin(), c.end(), std::greater<>());
}

Then sending an array to it would cause this compiler error:

error C2228: left of '.begin' must have class/struct/union

Header: <iterator>

Namespace: std

Show:
© 2014 Microsoft