Update language_basics.rst

docs/src/userguide/language_basics.rst

@@ -167,9 +167,10 @@ with string attributes if they are to be used after the function returns.
 C functions, on the other hand, can have parameters of any type, since they're
 passed in directly using a normal C function call.
 
-Functions declared using :keyword:`cdef`, like Python functions, will return a :keyword:`None`
+Functions declared using :keyword:`cdef` with Python object return type, like Python functions, will return a :keyword:`None`
 value when execution leaves the function body without an explicit return value. This is in
-contrast to C/C++, which leaves the return value undefined.
+contrast to C/C++, which leaves the return value undefined. 
+In the case of non-Python object return types, the equivalent of zero is returned, for example, 0 for ``int``, :keyword:`False` for ``bint`` and :keyword:`NULL` for pointer types.
 
 A more complete comparison of the pros and cons of these different method
 types can be found at :ref:`early-binding-for-speed`.