static/nonstatic data member declaration/definition

[Jeffrey]

My understanding is that if you write

class X {
int y;
static int z;
};

then you've defined (and declared) X and y, but you have only declared
(and not defined) z. If you'd like to actually define z, you also
need to add

int X::z;

Can anybody tell me the reason that the language was designed to be
like this? It seems it would be simpler if z were defined in the same
way as y, so presumably there's some good reason.

[James Kanze]

On Sep 29, 7:41 pm, Juha Nieminen <nos...@thanks. invalidwrote:

James Kanze wrote:

Mainly historical reasons, I suspect, but of course, if there is
an initializer (as there usually should be), you usually don't
want it in a header.

Aren't static variables always initialized to 0 (or null),
even without a specific initialization?

Variables with static lifetime are "zero initialized", but that
is of limited use. You don't really want to require that all
constants be 0.

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