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| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: A finalized program |
| Date | 2015-09-08 21:00 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <874mj4of4e.fsf@bsb.me.uk> (permalink) |
| References | <d93ca264-e41a-4f82-8c09-cd87731b2eed@googlegroups.com> <0b40a48e-3d88-46dd-adf2-275a33a87f65@googlegroups.com> <87r3m9nhwp.fsf@bsb.me.uk> <4371016b-309f-4f89-9b94-91088121f113@googlegroups.com> |
Malcolm McLean <malcolm.mclean5@btinternet.com> writes:
> On Tuesday, September 8, 2015 at 2:46:10 PM UTC+1, Ben Bacarisse wrote:
>>
>> But there is a problem with the way you use strlen. It's a function
>> that returns an unsigned value -- not an int (specifically a value of
>> type size_t used in C to represent sizes of things).
>>
> If you want another demonstration of the evils of size_t, here's some
> code I'm working on literally this minute.
>
> it's an undo / redo buffer with a "track" from the root, which was the
> document as created, to the current tip. There's also a "head" which
> shows where the next change will be inserted. So it's very simple
> boilerplate code, unfortunately C++.
>
> std::vector <Node *> getCurrentTrack(int *aHeadIndex) const
> {
> Node *node = mRoot;
> std::vector <Node *> answer;
> *aHeadIndex = -1;
> while(node)
> {
> answer.push_back(node);
> if(node == mHead)
> *aHeadIndex = (int) answer.size() -1;
> node = node->next;
> }
> return answer;
> }
>
> But if the index is a size_t, and the track is empty, what are we
> supposed to set aHeadIndex to?
But the index isn't a size_t -- someone (you?) chose int because you
want to use -1 as a special value. If you want the index to be a size_t
the design has to change. Set it to the final answer.size() (which is
guaranteed to be invalid) or, indeed, set it to (size_t)-1. What value
denotes "no head index" is part of the contract with the caller so the
designer chooses. You could even use the style of the standard
containers ans use an iterator.
> Or if the head isn't on the track
> (shouldn't happen, but maybe if the system is extended, you'll have
> "detached heads" as in git).
I don't follow this.
--
Ben.
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A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-08 04:13 -0700
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-08 04:19 -0700
Re: A finalized program fir <profesor.fir@gmail.com> - 2015-09-08 04:30 -0700
Re: A finalized program Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-08 14:45 +0100
Re: A finalized program Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-08 08:29 -0700
Re: A finalized program Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-08 08:52 -0700
Re: A finalized program Martin Shobe <martin.shobe@yahoo.com> - 2015-09-08 13:01 -0500
Re: A finalized program Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-08 21:00 +0100
Re: A finalized program Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-08 13:33 -0700
Re: A finalized program Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-09 00:28 +0100
Re: A finalized program Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-08 14:26 +0100
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-08 06:42 -0700
Re: A finalized program Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-08 20:50 +0100
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 01:47 -0700
Re: A finalized program jt@toerring.de (Jens Thoms Toerring) - 2015-09-08 13:41 +0000
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-10 01:31 -0700
Re: A finalized program jt@toerring.de (Jens Thoms Toerring) - 2015-09-10 10:39 +0000
Re: A finalized program David Thompson <dave.thompson2@verizon.net> - 2015-09-20 18:35 -0400
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-10 01:33 -0700
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-10 10:16 -0700
Re: A finalized program bartekltg <bartekltg@gmail.com> - 2015-09-10 20:08 +0200
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 02:05 -0700
Re: A finalized program Richard Heathfield <rjh@cpax.org.uk> - 2015-09-11 10:17 +0100
Re: A finalized program Richard Heathfield <rjh@cpax.org.uk> - 2015-09-11 10:19 +0100
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 02:28 -0700
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 02:29 -0700
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 02:19 -0700
Re: A finalized program Richard Heathfield <rjh@cpax.org.uk> - 2015-09-11 10:23 +0100
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 02:33 -0700
Re: A finalized program Keith Thompson <kst-u@mib.org> - 2015-09-11 14:11 -0700
Re: A finalized program jt@toerring.de (Jens Thoms Toerring) - 2015-09-11 21:39 +0000
Re: A finalized program bartekltg <bartekltg@gmail.com> - 2015-09-11 12:49 +0200
Re: A finalized program Richard Heathfield <rjh@cpax.org.uk> - 2015-09-10 23:31 +0100
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 02:15 -0700
Re: A finalized program jt@toerring.de (Jens Thoms Toerring) - 2015-09-10 22:37 +0000
Re: A finalized program Richard Heathfield <rjh@cpax.org.uk> - 2015-09-10 23:47 +0100
Re: A finalized program jt@toerring.de (Jens Thoms Toerring) - 2015-09-11 10:18 +0000
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 01:07 -0700
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 02:14 -0700
Re: A finalized program jt@toerring.de (Jens Thoms Toerring) - 2015-09-11 10:10 +0000
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 04:19 -0700
Re: A finalized program Barry Schwarz <schwarzb@dqel.com> - 2015-09-08 15:53 -0700
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 04:27 -0700
Re: A finalized program bartekltg <bartekltg@gmail.com> - 2015-09-11 14:05 +0200
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 04:42 -0700
Re: A finalized program bartekltg <bartekltg@gmail.com> - 2015-09-11 14:15 +0200
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 05:50 -0700
Re: A finalized program bartekltg <bartekltg@gmail.com> - 2015-09-11 15:00 +0200
Re: A finalized program Alla _ <modelling.data@gmail.com> - 2015-09-11 05:50 -0700
Re: A finalized program Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-11 13:46 +0100
Re: A finalized program Richard Heathfield <rjh@cpax.org.uk> - 2015-09-11 14:19 +0100
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