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From: fir <fir@grunge.pl>
Newsgroups: comp.lang.c
Subject: Re: while(T[l]<p & l<=r)
Date: Thu, 28 Mar 2024 17:28:41 +0100
Organization: i2pn2 (i2pn.org)
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Janis Papanagnou wrote:
> On 28.03.2024 13:18, fir wrote:
>> Janis Papanagnou wrote:
>>> On 27.03.2024 12:35, fir wrote:
>>>> tell me, is while(T[l]<p & l<=r) the same as while((T[l]<p)&&(l<=r))
>>>
>>> [...] If
>>> you don't want to operate on bits but want to express a boolean
>>> conjunction you should use '&&', though.
>>
>> [...]
>>
>> hovever i wopuld disagre to use "&&" instead "&" then
>> && look much worse
>
> (Well, I think that '+' looks much worse than '*', but in
> math expressions I use the _appropriate_ operator anyway.)
>
> Mind that '&' is *not* a syntactical variant of '&&'...
>
>> and probably & has no real disadvantages
>
> it is different to '&&', it has another semantic! As said,
> it's just by context-coincidence that it's equivalent _here_.
>
>> (i mean no
>> bigger that the intention that && should be use for boolean - which
>> probably comes from later c not oryginal young c
>
> Original K&R C had '&' for bit-operations and '&&' for boolean
> operations.
>
> While, say, 'x<y & u<v' works effectively as 'x<y && u<v' (as
> said, because of the evaluations to 0 and 1, general boolean
> predicates, like 'p() & q()' is not the same as 'p() && q()',
> even if you can use 'p()' and 'q()' in 'if'-conditions as per
> the C semantics of booleans (or integers used as booleans).
>
> You often see code like,say, 'x=length(s); y=length(t);' and
> compare non-emptiness of the strings with 'if (x)' or with
> 'if (y)'. If you combine that condition by 'if (x & y)' you
> will get wrong results, but 'if (x && y)' would be correct.
>

how, if string ate empty then the pionters are nulls to
null&null should work ok imo

> '&' is for bit-operations in scalars, '&&' is for booleans
> (for logical operations, bool x bool -> bool).
>
>>
>> so i probably plan to stick to &
>
> But why stick to a bit-value operator where you want a
> boolean logic operator? - You just confuse readers of your
> code and unnecessarily introduce error-prone code.
>
> (But you can of course do as you like.)
>
> Janis
>
becouse this && is ugly i think the addition of && is kinda error
in language