A type that describes a specialization of the template class basic_string with elements of type wchar_t.
The following are equivalent declarations:
For a list of string constructors, see basic_string::basic_string.
The size of wchar_t is implementation-defined. If your code depends on wchar_t to be a certain size, check your platform's implementation (for example, with sizeof(wchar_t)). If you need a string character type with a width that is guaranteed to remain the same on all platforms, use string, u16string, or u32string.