Re: [9fans] Don't Plan 9 C compiler initialize the rest of member of a struct?

[Skip Tavakkolian <skip.tavakkolian@gmail.com>]

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like this:

#include <u.h>
#include <stdio.h>

struct option {
int n;
char *s;
int flags;
};


int main(void)
{
struct option opt = { 1, "test" };
static struct option opt2;

printf("%d %s %x\n", opt.n, opt.s, opt.flags);
printf("%x\n", opt2.flags);
return 0;
}


On Tue, Apr 2, 2019 at 8:02 AM Skip Tavakkolian <skip.tavakkolian@gmail.com>
wrote:

> I interpret it as: initialize it like a static variable.
>
> On Tue, Apr 2, 2019 at 7:53 AM Kyohei Kadota <lufia@lufia.org> wrote:
>
>> Thank you for a reply.
>>
>> I read spec on http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf
>> then I'm confusing.
>> This spec describes Initialization:
>>
>> > 6.7.8 Initialization, p127
>> >
>> > 19 The initialization shall occur in initializer list order, each
>> initializer provided for a
>> > particular subobject overriding any previously listed initializer for
>> the same subobject;132)
>> > all subobjects that are not initialized explicitly shall be initialized
>> implicitly the same as
>> > objects that have static storage duration.
>>
>> What is "be initialized implicitly the same as objects that have
>> static storage duration" mean?
>>
>> 2019年4月2日(火) 9:27 Jeremy O'Brien <neutral@fastmail.com>:
>> >
>> > On Mon, Apr 1, 2019, at 11:33, Kyohei Kadota wrote:
>> > > Hi, 9fans. I use 9legacy.
>> > >
>> > > About below program, I expected that flags field will initialize to
>> > > zero but the value of flags was a garbage, ex, "f8f7".
>> > > Is this expected?
>> > >
>> > > ```
>> > > #include <stdio.h>
>> > >
>> > > struct option {
>> > >     int n;
>> > >     char *s;
>> > >     int flags;
>> > > };
>> > >
>> > > int
>> > > main(void)
>> > > {
>> > >     struct option opt = {1, "test"};
>> > >     printf("%d %s %x\n", opt.n, opt.s, opt.flags);
>> > >     return 0;
>> > > }
>> > > ```
>> > >
>> > >
>> >
>> > According to C99: "If an object that has automatic storage duration is
>> not initialized explicitly, its value is indeterminate."
>> >
>> > Stack variable == automatic storage duration. This appears to be
>> correct behavior to me.
>> >
>>
>>

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