std:: begin, std:: cbegin

Returns an iterator to the beginning of the given range.

Parameters

Return value

Exceptions

Overloads

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

Similar to the use of swap (described in Swappable ), typical use of the begin function in generic context is an equivalent of using std :: begin ; begin ( arg ) ; , which allows both the ADL -selected overloads for user-defined types and the standard library function templates to appear in the same overload set.

template<typename Container, typename Function>
void for_each(Container&& cont, Function f)
{
    using std::begin;
    auto it = begin(cont);
    using std::end;
    auto end_it = end(cont);
    while (it != end_it)
    {
        f(*it);
        ++it;
    }
}

Notes

The non-array overloads exactly reflect the behavior of C::begin . Their effects may be surprising if the member function does not have a reasonable implementation.

std::cbegin is introduced for unification of member and non-member range accesses. See also LWG issue 2128 .

If C is a shallow-const view, std::cbegin may return a mutable iterator. Such behavior is unexpected for some users. See also P2276 and P2278 .

Example

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

+3
-5

See also