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()

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

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