The object of class wostream that represents the standard logging stream oriented to wide characters (of type wchar_t). It corresponds, along with wcerr, to the C stream stderr. The standard logging stream is a destination of characters determined by the environment. This destination may be shared by more than one standard object (such as wcout or wcerr).
Object of a basic_ostream class, characters can be written to it either as formatted data using the insertion operator (operator<<) or as unformatted data, using member functions such as write.
Following is the declaration for std::wclog.
extern basic_ostream<wchar_t> wclog;
By default, clog is synchronized with stderr.
A program should not mix output operations on wclog with output operations on clog or cerr (or with other narrow-oriented output operations on stderr): Once an output operation has been performed on either, the standard logging stream acquires an orientation (either narrow or wide) that can only be safely changed by calling freopen on stderr..