C struct construct question

[Behdad Esfahbod]

On Tue, 18 Apr 2006, John Vetterli wrote:

> On Tue, 18 Apr 2006, Peter wrote:
> > I found an unusual C construct in Asterisk source code and I am looking for
> > an explanation. Of course I cannot find one online. Here is a quote:
> > static const struct ast_channel_tech local_tech = {
> >        .type = type,
> >        .description = tdesc,
> >        .capabilities = -1,
> >        .requester = local_request,
> >        .send_digit = local_digit,
> > 	.call = local_call,
> >        .hangup = local_hangup,
> >        .answer = local_answer,
> >        .read = local_read,
> >        .write = local_write,
> >        .exception = local_read,
> >        .indicate = local_indicate,
> >        .fixup = local_fixup,
> >        .send_html = local_sendhtml, };
> > how does this work ? References ?
>
> This syntax specifies which field in struct ast_channel_tech receives
> which value, as opposed to having to list the the values in the same order
> as they were declared in. Have a look at:
>
>    http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Designated-Inits.html
>
> That web page is for gcc version 4.1.0, but that feature seems to have
> been in gcc since the first 3.x release.

Yes, and this is a C99 addition.


> HTH
> JV

--behdad
http://behdad.org/

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