The object of class wistream that represents the standard input stream oriented to wide characters (of type wchar_t). It corresponds to the C stream stdin. The standard input stream is a source of characters determined by the environment. It is generally assumed to be input from an external source, such as the keyboard or a file.
Object of a basic_istream class, characters can be retrieved either as formatted data using the extraction operator (operator>>) or as unformatted data, using member functions such as read.
Following is the declaration for std::wcin.
extern basic_istream<wchar_t> wcin;
By default, wcin is synchronized with stdin.
A program should not mix input operations on wcin with input operations on cin (or with other narrow-oriented input operations on stdin): Once an input operation has been performed on either, the standard input stream acquires an orientation (either narrow or wide) that can only be safely changed by calling freopen on stdin.