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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: trying a linked list |
| Date | 2016-05-08 14:56 -0700 |
| Organization | None to speak of |
| Message-ID | <lnlh3kw6w4.fsf@kst-u.example.com> (permalink) |
| References | (8 earlier) <ngo0s4$g9h$1@dont-email.me> <87d1owgyev.fsf@bsb.me.uk> <ngo3q2$r9a$1@dont-email.me> <87twi8fikb.fsf@bsb.me.uk> <ngoa7k$jg5$1@dont-email.me> |
"Bill Cunningham" <nospam@nspam.invalid> writes:
> "Ben Bacarisse" <ben.usenet@bsb.me.uk> wrote in message
> news:87twi8fikb.fsf@bsb.me.uk...
>> "Bill Cunningham" <nospam@nspam.invalid> writes:
>>> "Ben Bacarisse" <ben.usenet@bsb.me.uk> wrote in message
>>> news:87d1owgyev.fsf@bsb.me.uk...
[...]
>>>> int main(void)
>>>> {
>>>> struct node n4 = {4, NULL},
>>>> n3 = {3, &n4},
>>>> n2 = {2, &n3},
>>>> n1 = {1, &n2};
>>>
>>> This above is very intriguing code. If I can decypher it it
>>> looks like n4 is of type "struct node" Now the members of the struct
>>> {4,NULL} that I've never seen.
>>
>> You need to read a book about C then. I can't imagine any book about C
>> that does not show a struct object being initialised.
>>
>>> don't member have to have there own types?
>>
>> Yes, the types are int (for the first member) and struct node * (for the
>> second member). That's why {4, NULL} is a reasonable initialiser.
>
> I've never seen a struct initialized with members and no explicit
> declaration of types ergo,
>
> struct node{
> int number;
> Where you have,
>
> struct node {number}; //For example as compared to what I'm doing. I know
> your calling yours n4.
You've confused a struct *definition* with a struct object
*initialization*.
This:
struct node {
int number;
struct node *next;
};
defines the type "struct node". It specifies the names and types of its
members.
This:
struct node n4 = { 4, NULL };
defines an object "n4"; the "{ 4, NULL }" part is an *initializer*.
Initializers don't need to specify the types of the members; that's
already specified by the struct definition.
> I erased and rewrote code up to where there's an error,
> #include <stdio.h>
> #include <stdlib.h>
>
> struct node {
> int number;
> struct node *next;
> };
>
>
> int main()
> {
> struct node base;
> struct node *sp;
> sp = &base;
> sp->number = 1;
> printf("%d\n", *sp);
As I discussed in another followup, the above is wrong.
> sp->next = NULL;
> sp = malloc(sizeof *sp);
> sp->next->number = 2;
> printf("%d\n", *sp);
> }
>
> I'm not quite sure why the malloc isn't working as others have told me to
> use and what I think I'm reading.
The malloc() should have worked just fine. What makes you think it
didn't? It allocated space for a new "struct node" object that sp then
points to (though you didn't check that the allocation succeeded). But,
as I've also mentioned, sp->next is uninitialized, which is why
sp->next->number = 2;
is likely to blow up in your face.
> And I did try this and got an error,
>
> struct node{
> int number=0;
> ...
>
> The compiler didn't like it. I don't know if it's C99 or C11. It has
> inittypes.h and complex.h and stdint.h so C11 probably.
You cannot specify initial values in a struct definition. That's true
for alll versions of C. (It would be nice if you could, but it happens
that that's not a feature of the language.)
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-07 17:06 -0400
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-07 17:32 -0400
Re: trying a linked list Rosario19 <Ros@invalid.invalid> - 2016-05-07 23:44 +0200
Re: trying a linked list "martin.ambuhl" <mambuhl@earthlink.net> - 2016-05-07 19:49 -0400
Re: trying a linked list Richard Heathfield <rjh@cpax.org.uk> - 2016-05-08 07:46 +0100
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-07 14:35 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-07 17:53 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-07 15:01 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-07 19:18 -0400
Re: trying a linked list Jerry Stuckle <jstucklex@attglobal.net> - 2016-05-07 19:28 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-07 16:40 -0700
Re: trying a linked list Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-05-07 17:15 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-07 20:25 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-07 20:10 -0700
Re: trying a linked list Richard Heathfield <rjh@cpax.org.uk> - 2016-05-08 07:53 +0100
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-08 14:19 -0700
Re: trying a linked list Manfred <mx2927@gmail.com> - 2016-05-08 18:45 +0200
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-08 17:21 -0400
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-08 14:38 -0400
Re: trying a linked list Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-05-08 20:08 +0100
Re: trying a linked list Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-05-08 20:26 +0100
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-08 17:22 -0400
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-08 15:28 -0400
Re: trying a linked list Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-05-08 20:36 +0100
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-08 17:17 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-08 14:56 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-08 18:17 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-08 19:31 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 14:59 -0400
Re: trying a linked list Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-05-08 23:22 +0100
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 14:46 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-08 14:32 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-08 18:05 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-08 14:26 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 13:50 -0400
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 14:08 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-09 11:38 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 14:50 -0400
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 14:51 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-09 13:51 -0700
Re: trying a linked list Ken Brody <kenbrody@spamcop.net> - 2016-05-09 17:53 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-09 13:47 -0700
Re: trying a linked list "Osmium" <r124c4u102@comcast.net> - 2016-05-09 15:58 -0500
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 17:13 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-09 14:35 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 17:40 -0400
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 17:41 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-09 15:10 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 22:02 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-09 21:17 -0700
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-09 22:31 -0400
Re: trying a linked list "Bill Cunningham" <nospam@nspam.invalid> - 2016-05-07 20:30 -0400
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-07 20:06 -0700
Re: trying a linked list Richard Heathfield <rjh@cpax.org.uk> - 2016-05-08 07:50 +0100
Re: trying a linked list BartC <bc@freeuk.com> - 2016-05-08 10:33 +0100
Re: trying a linked list Richard Heathfield <rjh@cpax.org.uk> - 2016-05-08 10:39 +0100
Re: trying a linked list BartC <bc@freeuk.com> - 2016-05-08 11:14 +0100
Re: trying a linked list Richard Heathfield <rjh@cpax.org.uk> - 2016-05-08 13:34 +0100
Re: trying a linked list BartC <bc@freeuk.com> - 2016-05-08 14:39 +0100
Re: trying a linked list Richard Heathfield <rjh@cpax.org.uk> - 2016-05-08 14:51 +0100
Re: trying a linked list Siri Cruise <chine.bleu@yahoo.com> - 2016-05-08 07:30 -0700
Re: trying a linked list Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-05-08 10:36 +0100
Re: trying a linked list Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-05-08 02:49 -0700
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-08 14:17 -0700
Re: trying a linked list Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-05-08 14:36 -0700
Re: trying a linked list Keith Thompson <kst-u@mib.org> - 2016-05-08 14:57 -0700
Re: trying a linked list Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-05-09 13:28 -0700
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