or a C function that returns a pointer
to an integer.  The resulted integer value of the result can be obtained by
<TT>(sys:peek result :long)</TT>, where result is a variable set to the
result of the C function.
You may also specify <TT>(:foreign-string [n])</TT> for C functions
that return a string or a struct.
The result is a foreign-string whose content is held somewhere outside
EusLisp control.
If the result string is null-terminated and the length of the string
is known by strlen, you don't need to sp