Returns a const iterator that addresses the first element in the range.
With the return value of cbegin, the elements in the range cannot be modified.
You can use this member function in place of the begin() member function to guarantee that the return value is const_iterator. Typically, it's used in conjunction with the auto type deduction keyword, as shown in the following example. In the example, consider Container to be a modifiable (non-const) container of any kind that supports begin() and cbegin().