In bf(C++) all zero values are coded as tt(0). In bf(C) ti(NULL) is often used
in the context of pointers. This difference is purely stylistic, though one
that is widely adopted. In bf(C++) tt(NULL) should be avoided (as it is a
i(macro), and macros can --and therefore should-- easily be avoided in
bf(C++), see also section ref(GENCONST)). Instead tt(0) can almost always be
used.

Almost always, but not always. As bf(C++) allows function overloading
(cf. section ref(FunctionOverloading)) the programmer might be confronted with
an unexpected function selection in the situation shown in section
ref(FunctionOverloading):
        verbinclude(-a examples/overload.cc)

In this situation a programmer intending to call tt(show(char const *)) might
call tt(show(0)). But this doesn't work, as 0 is interpreted as tt(int) and so
tt(show(int)) is called. But calling tt(show(NULL)) doesn't work either, as
bf(C++) usually defines ti(NULL) as 0, rather than tt(((void *)0)). So,
tt(show(int)) is called once again. To solve these kinds of problems the new
bf(C++) standard introduces the keyword ti(nullptr) representing the 0
pointer. In the current example the programmer should call tt(show(nullptr))
to avoid the selection of the wrong function. The tt(nullptr) value can also
be used to initialize pointer variables. E.g.,
        verb(    int *ip = nullptr;      // OK
    int value = nullptr;    // error: value is no pointer)

