std::basic_string::rbegin, std::basic_string::crbegin
From cppreference.com
                    
                                        
                    < cpp | string | basic string
                    
                                                            
                    |   iterator rbegin(); 
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|   const_iterator rbegin() const; 
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|   const_iterator crbegin() const; 
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(since C++11) | |
Returns a reverse iterator to the first character of the reversed string. It corresponds to the last character of the non-reversed string.
Contents | 
[edit] Parameters
(none)
[edit] Return value
reverse iterator to the first character
[edit] Complexity
Constant
[edit] See also
|    (C++11)  | 
   returns a reverse iterator to the end   (public member function)  |