Comments on: On initializing static variables

By: Vincent Gable

Vincent Gable — Tue, 23 Mar 2010 22:43:53 +0000

If I’m reading the last provision correctly, then you could get into trouble if the first member in a union was shorter than the longest, because only the first member of the union is guaranteed to be initialized to 0.

static union {
uint8_t eight;
uint64_t sixtyfour;
} onlyEightBitsOfMeMustBeZero;

In practice, I’d imagine the storage for a static variable is always filled with 0x00 though.

By: Patrick Stein

Patrick Stein — Mon, 19 Feb 2007 22:45:21 +0000

That’s what I thought was standard for years, but got bitten on Intel lately. At least this switch helps.

By: Daniel Jalkut

Daniel Jalkut — Thu, 04 Jan 2007 16:19:39 +0000

It’s worth pointing out that C99 compliance is not on by default in new Xcode projects.

However, your test case seems to produce the same zero-ness even when I turn off the flag. Wouldn’t count on it, though.

Daniel