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Groups > comp.lang.c > #126368
| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Count string in string with loop increase 2, why is this not faster? |
| Date | 2018-02-07 12:02 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <87372dhus1.fsf@bsb.me.uk> (permalink) |
| References | (16 earlier) <aToeC.470372$oD1.406285@fx44.am4> <64044642-4874-4fcb-94ae-e8271c184faa@googlegroups.com> <pmseC.673377$QL6.442615@fx20.am4> <ln8tc51poo.fsf@kst-u.example.com> <UeBeC.603044$9X4.108846@fx02.am4> |
bartc <bc@freeuk.com> writes:
> On 07/02/2018 02:47, Keith Thompson wrote:
>> bartc <bc@freeuk.com> writes:
>>> On 07/02/2018 00:43, Bart Smissaert wrote:
>>>> For some reason your function gets quite slow (some 4-5x) when you
>>>> pick a character where the second byte is not zero, eg Char(128).
>>>
>>> That one should still have the second byte zero unless wchar_t is
>>> signed. But on Windows it appears to be unsigned. Try this code:
>>>
>>> double x;
>>> wchar_t c;
>>>
>>> c=128;
>>> x=c;
>>>
>>> printf("%f\n",x);
>>>
>>> It should display 128.0000.
>>
>> The only way that could display a value other than 128.000000
>> is if wchar_t is signed and only 8 bits. (In that case it would
>> most likely print -128.000000.)
>
> Yeah, that was some confusion on my part.
>
>> If you want to see the characteristics of wchar_t on your system,
>> try this:
>
> The same method works but you have to use:
>
> c = 32768;
Not on my system. You are assuming that wchar_t is two bytes, and if
wchar_t is two bytes and signed, that the implementation does what you
expect with an overflowing signed integer conversion.
Both of these may be reasonable in the context, but it is so easy to
test if an integer type is signed in C that making these assumptions
seems unnecessary: (T)-1 will be positive if T if an unsigned integer
type.
--
Ben.
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Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 00:00 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 11:29 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 03:37 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 12:29 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 04:37 -0800
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-03 13:41 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 06:38 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 15:13 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 15:19 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 07:41 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-03 11:38 -0500
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-03 13:50 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-03 11:34 +0000
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-03 11:32 -0500
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-03 16:41 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 09:02 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 09:06 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-03 12:39 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-03 11:56 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-03 19:54 -0500
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-03 18:00 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 01:53 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 13:23 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 11:11 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 14:48 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 12:17 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-04 21:53 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 14:35 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-04 23:32 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-05 06:26 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 16:59 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-05 09:44 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 18:28 +0000
Re: Count string in string with loop increase 2, why is this not faster? scott@slp53.sl.home (Scott Lurndal) - 2018-02-05 18:41 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 20:08 +0000
Re: Count string in string with loop increase 2, why is this not faster? scott@slp53.sl.home (Scott Lurndal) - 2018-02-05 21:27 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 22:04 +0000
Re: Count string in string with loop increase 2, why is this not faster? scott@slp53.sl.home (Scott Lurndal) - 2018-02-05 22:38 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-06 01:34 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 06:39 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-06 18:07 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 12:34 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-06 21:12 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 13:42 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 16:43 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 01:10 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-06 18:47 -0800
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-07 15:13 +0100
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 14:48 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 17:13 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 17:27 +0000
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-07 17:01 +0100
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 02:00 -0800
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 12:02 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-07 14:46 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 13:56 +0000
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 11:17 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-06 23:59 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 05:10 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 11:01 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 14:24 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 14:44 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 22:59 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-07 15:20 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-07 23:31 +0000
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-07 15:32 -0800
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-07 16:05 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-05 15:29 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 17:41 -0500
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-04 23:11 +0000
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 23:45 -0500
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-04 15:11 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-04 23:37 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-04 18:08 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 23:12 -0500
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-05 13:08 +0100
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-05 08:24 -0500
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-05 14:39 +0100
Re: Count string in string with loop increase 2, why is this not faster? Robert Wessel <robertwessel2@yahoo.com> - 2018-02-05 10:37 -0600
Re: Count string in string with loop increase 2, why is this not faster? supercat@casperkitty.com - 2018-02-05 13:52 -0800
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-05 22:29 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-05 09:01 -0800
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-05 18:44 +0000
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-06 10:42 +0100
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-06 11:17 +0000
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-06 08:40 -0500
Re: Count string in string with loop increase 2, why is this not faster? bartc <bc@freeuk.com> - 2018-02-06 14:08 +0000
Re: Count string in string with loop increase 2, why is this not faster? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-02-06 14:42 +0000
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-06 12:35 -0800
Re: Count string in string with loop increase 2, why is this not faster? David Brown <david.brown@hesbynett.no> - 2018-02-06 23:04 +0100
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 17:35 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 14:38 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 17:57 -0500
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 15:22 -0800
Re: Count string in string with loop increase 2, why is this not faster? Bart Smissaert <bart.smissaert@gmail.com> - 2018-02-04 12:19 -0800
Re: Count string in string with loop increase 2, why is this not faster? Richard Damon <Richard@Damon-Family.org> - 2018-02-04 16:42 -0500
Re: Count string in string with loop increase 2, why is this not faster? Keith Thompson <kst-u@mib.org> - 2018-02-03 13:38 -0800
Re: Count string in string with loop increase 2, why is this not faster? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-02-03 22:03 +0000
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