From cppreference.com
classcodecvt_base;The class
provides the conversion status constants which are inherited and used by the
facets.
Member types
Member type Definition enumresult{ok,partial,error,noconv};Unscoped enumeration type Value Explanation okconversion was completed with no error partialnot all source characters were converted errorencountered an invalid character noconvno conversion required, input and output types are the same Notes
The value
is used to indicate that either the destination range is too short to receive the results of the conversion or the input is truncated in the middle of an otherwise valid multibyte character.
See also
converts between character encodings, including UTF-8, UTF-16, UTF-32
(class template)