0
-1
unpredictable
none of these
an identifier may start with an underscore
an identifier may end with an underscore
IF is a valid identifier
All of the above
during external variable definition, storage is set aside by the compiler
during external variable declaration, no storage is set aside by the compiler
the use of external variables may make debugging difficult
it is binary representation of a character in the extended binary set
it is of integer type wchar_t
end of file is represented by WEOF
they provide a way for two way communication between functions
their scope extends from the point of definition through the remainder of the program
if they are not initialized, they will be initialised to zero