Standard library header <cuchar>
From cppreference.com
                    
                                        
                    
                    
                                                            
                    This header was originally in the C standard library as <uchar.h>.
This header is part of the null-terminated multibyte strings library.
 Macros | 
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|    __STDC_UTF_16__  | 
   indicates that UTF-16 encoding is used by mbrtoc16 and c16rtomb  (macro constant)  | 
|    __STDC_UTF_32__  | 
   indicates that UTF-32 encoding is used by mbrtoc32 and c32rtomb  (macro constant)  | 
 Functions | 
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|    (C++11) 
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   generate the next 16-bit wide character from a narrow multibyte string   (function)  | 
|    (C++11) 
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   convert a 16-bit wide character to narrow multibyte string  (function)  | 
|    (C++11) 
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   generate the next 32-bit wide character from a narrow multibyte string  (function)  | 
|    (C++11) 
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   convert a 32-bit wide character to narrow multibyte string  (function)  |