Three-dimensional array initialization

Question

In a bit of code I'm looking at, a 3D array has been initialized like so:

static const char codeset[6][256][10] = {
    [0] = { [0x20] = " ",
    [0x21] = "!",
    [0x22] = "&quot;",
    [0x23] = "#",
}};

(It does go on to initialize the rest of the cells, I've cut it short to show something readable.)

This does not compile. Is it supposed to? What's going on here?

Compiles for me correctly (gcc 4.5.1). If you're on GCC, you can add -std=c99 to your command line just to be on the safe side, as it's a C99 extension. — Kos
– Kos, Commented Nov 29, 2010 at 11:51
Alas, I'm in Visual studio, and apparently it's not going to work there: eggheadcafe.com/software/aspnet/34012666/… — dkb
– dkb, Commented Nov 29, 2010 at 12:05

Gunther Piez · Accepted Answer · 2010-11-29 11:51:34Z

3

You are using C99 initializers, but your compiler does not support C99 or C99 is not enabled.

answered Nov 29, 2010 at 11:51

Gunther Piez

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qrdl · Accepted Answer · 2010-11-29 14:33:36Z

2

You are trying to use C99 initializers, but most likely your compiler isn't C99-compliant, otherwise it would work.

edited Nov 29, 2010 at 14:33

answered Nov 29, 2010 at 11:44

qrdl

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2 Comments

Kos Over a year ago

Good link, but unless my reading skills are bugged, it states that it's C99 extension, not GCC extension. GCC extends upon this by allowing to initialize ranges. +1 anyway as the link explains what's going on here. I didn't know that one too :)

qrdl Over a year ago

@Kos Thanks, corrected. I was so much sure it is GCC-only so I didn't read thoughtfully.

jim mcnamara · Accepted Answer · 2010-11-29 10:47:21Z

0

As a guess, it trying to create the "alphabet" for xml string ASCII data. The " (double quote) character in xml is represented as &quot. So the [0][0 - 255] group is xml.

It looks like an equivalence table. It translates from xml to ASCII or whatever.

answered Nov 29, 2010 at 10:47

jim mcnamara

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dkb Over a year ago

Heh, maybe I was unclear - I know what the point of the array is, I want to know what's the problem with the initialization (Which, from what I've read, isn't actually supposed to work like that).

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