cpp/locale/codecvt/unshift

@1@ Public member function, calls the member function of the most derived class.

@2@ If the encoding represented by this facet is state-dependent, and  represents a conversion state that is not the initial shift state, writes the characters necessary to return to the initial shift state. The characters are written to a character array whose first element is pointed to by. No more than characters are written. The parameter is updated to point one past the last character written.

Return value
A value of type std, indicating the success status as follows: