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| From | BartC <bc@freeuk.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Counted strings |
| Date | 2016-12-06 02:13 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <o256p9$rek$1@dont-email.me> (permalink) |
| References | (8 earlier) <2cdca7c0-657d-4d61-8457-94ef01f3f4cf@googlegroups.com> <o23vu2$eaq$1@dont-email.me> <7520b145-f095-473c-a117-d89ef8feb590@googlegroups.com> <o244gj$9l$1@dont-email.me> <87shq2gh64.fsf@bsb.me.uk> |
On 05/12/2016 22:11, Ben Bacarisse wrote:
> BartC <bc@freeuk.com> writes:
>> Take this simple implementation of a counted string type and character
>> append routine (see below).
>>
>> To append 'A' 10 million times starting with an empty string took
>> about 13 seconds (gcc -O3, Windows CRT).
>>
>> My little *interpreted* language took under 0.2 seconds.
>> Yes, the C can be nearly as fast, with enough effort. But it's about
>> algorithms rather than language.
> Yes, algorithms and data structures. The usual method is to store the
> size and multiply it by a constant factor when reallocating. When you
> do that, it's also faster to zero the new store in one go rather than
> writing a null byte on every append. Here's that version with added
> error-checking:
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
>
> typedef struct {
> char* str;
> int length;
> int size;
> } Cstr;
>
> int appendchar(Cstr *s, char c)
> {
> if (s->length + 1 >= s->size) {
> int nsz = s->size * 3 / 2 + 16;
> char *nstr = realloc(s->str, nsz);
> if (!nstr) return 0;
> memset(nstr + s->size, 0, nsz - s->size);
> s->size = nsz;
> s->str = nstr;
> }
> s->str[s->length++] = c;
> return 1;
> }
>
> int main(int argc, char **argv)
> {
> int len = argc > 1 ? atoi(argv[1]) : 500*1000*1000;
> Cstr s = {0};
>
> for (int i = 0; i < len && appendchar(&s, 'A'); ++i);
>
> printf("s.length = %d\n", s.length);
> printf("strlen(s.str) = %zu\n", strlen(s.str));
> }
I ran your code with these results for 500M (on Windows):
32-bit 64-bit
gcc -O3 2.2 1.5 seconds
mid-Cs -O ~4.5 3.5 [Pelles C, lccwin, DMC]
Tiny C 7.4 6.5
MSVC /O2 1.8 -- [2008]
gcc -O0 -- 4.8
Interpreted -- 8.4 [Fastest]
I'm not sure why 64 bits makes such a difference (usually it slows it
down!).
(I took out the memset, and the strlen call, as the interpreted version
doesn't use a zero terminator.)
So with dedicated allocation code, the C can easily beat the interpreted
program. But the latter still isn't bad considering it also has to take
care of decoding four byte-code instructions, do a dynamic type dispatch
and deal with reference counts for each iteration! Also it has to use
the same memory allocator as other objects, not a dedicated one.
However, it uses some ASM code to get this speed.)
--
Bartc
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Counted strings jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-03 23:58 +0100
Re: Counted strings supercat@casperkitty.com - 2016-12-03 15:40 -0800
Counted stringsl Thiago Adams <thiago.adams@gmail.com> - 2016-12-03 15:40 -0800
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-04 00:20 +0000
Re: Counted strings Richard Damon <Richard@Damon-Family.org> - 2016-12-03 21:26 -0500
Re: Counted strings jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-04 18:11 +0100
Re: Counted strings Mark Storkamp <mstorkamp@yahoo.com> - 2016-12-04 19:25 -0600
Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-03 18:57 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 16:33 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-04 07:52 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 17:10 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-04 10:14 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 20:20 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-04 16:49 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-05 10:40 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 05:51 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-05 16:10 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 07:38 -0800
Re: Counted strings Melzzzzz <mel@zzzzz.com> - 2016-12-05 16:56 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 08:04 -0800
Re: Counted strings Melzzzzz <mel@zzzzz.com> - 2016-12-05 17:16 +0100
Re: Counted strings Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-05 16:12 -0500
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 13:24 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 10:53 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 03:52 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 13:32 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 04:48 -0800
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 13:42 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 05:16 -0800
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 14:39 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 05:24 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 05:41 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 05:47 -0800
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 14:48 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 05:54 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 06:21 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 06:24 -0800
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 18:06 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 10:19 -0800
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 19:45 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 11:10 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 12:58 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 14:08 -0800
Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-06 11:25 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 05:28 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 16:21 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 07:29 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 07:39 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 08:32 -0800
Re: Counted strings fir <profesor.fir@gmail.com> - 2016-12-06 08:32 -0800
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 16:28 +0000
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 08:34 -0800
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 18:27 +0000
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 10:36 -0800
Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 08:19 +1300
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 11:22 -0800
Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 08:26 +1300
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 19:36 +0000
Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 08:41 +1300
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 11:48 -0800
Re: Counted strings Thiago Adams <thiago.adams@gmail.com> - 2016-12-05 11:59 -0800
Re: Counted strings jameskuyper@verizon.net - 2016-12-05 12:12 -0800
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 12:18 -0800
Re: Counted strings jameskuyper@verizon.net - 2016-12-05 13:17 -0800
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 13:29 -0800
Re: Counted strings jameskuyper@verizon.net - 2016-12-05 15:37 -0800
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 15:43 -0800
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 13:40 +0100
Re: Counted strings "James R. Kuyper" <jameskuyper@verizon.net> - 2016-12-06 12:00 -0500
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 10:09 -0800
Re: Counted strings Jerry Stuckle <jstucklex@attglobal.net> - 2016-12-06 13:33 -0500
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-06 21:24 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-06 12:56 -0800
Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-05 12:22 -0800
Re: Counted strings supercat@casperkitty.com - 2016-12-05 08:36 -0800
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 17:31 +0000
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-05 22:07 +0100
Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 10:14 +1300
Re: Counted strings Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-05 22:11 +0000
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-06 02:13 +0000
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-05 21:57 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 13:01 -0800
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 21:22 +0000
Re: Counted strings Ian Collins <ian-news@hotmail.com> - 2016-12-06 10:25 +1300
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-05 21:36 +0000
Re: Counted strings jacobnavia <jacob@jacob.remcomp.fr> - 2016-12-05 22:33 +0100
Re: Counted strings "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-12-05 17:03 -0500
Re: Counted strings supercat@casperkitty.com - 2016-12-04 08:57 -0800
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-04 20:19 +0100
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 20:24 +0100
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-04 20:37 +0100
Re: Counted strings David Brown <david.brown@hesbynett.no> - 2016-12-04 21:04 +0100
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-04 21:22 +0100
Re: Counted strings BartC <bc@freeuk.com> - 2016-12-04 22:37 +0000
Re: Counted strings David Thompson <dave.thompson2@verizon.net> - 2016-12-10 22:42 -0500
Re: Counted strings Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-10 23:17 -0800
Re: Counted strings Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-11 11:48 +0000
Re: Counted strings Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-11 04:40 -0800
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-11 10:56 +0100
Re: Counted strings Robert Wessel <robertwessel2@yahoo.com> - 2016-12-05 15:47 -0600
Re: Counted strings Gareth Owen <gwowen@gmail.com> - 2016-12-05 22:01 +0000
Re: Counted strings Robert Wessel <robertwessel2@yahoo.com> - 2016-12-05 22:28 -0600
Re: Counted strings "Chris M. Thomasson" <invalid@invalid.invalid> - 2016-12-05 20:18 -0800
Re: Counted strings Robert Spanjaard <spamtrap@arumes.com> - 2016-12-06 11:05 +0100
Re: Counted strings luser droog <luser.droog@gmail.com> - 2016-12-04 13:13 -0800
Re: Counted strings Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-05 09:30 -0800
Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-05 09:41 -0800
Re: Counted strings Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-06 11:19 -0800
Re: Counted strings Keith Thompson <kst-u@mib.org> - 2016-12-06 11:44 -0800
Re: Counted strings Tim Rentsch <txr@alumni.caltech.edu> - 2016-12-10 10:29 -0800
Re: Counted strings supercat@casperkitty.com - 2016-12-10 11:08 -0800
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