Re: Count string in string with loop increase 2, why is this not faster?

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From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c
Subject	Re: Count string in string with loop increase 2, why is this not faster?
Date	Tue, 06 Feb 2018 18:47:19 -0800
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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.)

If you want to see the characteristics of wchar_t on your system,
try this:

#include <stdio.h>
#include <stddef.h>
#include <limits.h>
#include <stdint.h>
int main(void) {              
    printf("wchar_t is %zu bits, %s\n",
           CHAR_BIT * sizeof (wchar_t),
           (wchar_t)-1 < (wchar_t)0 ? "signed" : "unsigned");
    printf("WCHAR_MIN = %ld\n", (long)WCHAR_MIN);
    printf("WCHAR_MAX = %ld\n", (long)WCHAR_MAX);
}

-- 
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"

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