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Re: Do variables need to be initialized?

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On 08/06/2015 14:21, Ben Bacarisse wrote:
> Bartc <bc@freeuk.com> writes:
>
>> On 08/06/2015 13:39, gwowen wrote:
>>> On Saturday, June 6, 2015 at 10:06:22 PM UTC+1, Joe Pfeiffer wrote:
>>>
>>>> If the search is non-trivial, the function is too long.  If the
>>>> variables aren't all declared together, you still have to scan the
>>>> 20-line function to figure out where they are.  That search is trivial,
>>>> but still present.
>>>
>>> Nope.  If the function is short, and declarations are at
>>> point-of-first-use then the majority of time the search is non
>>> existent - the declaration is right there within a line or two of
>>> the use.
>>>
>>
>> Which expression is easier to take in:
>>
>>   double a,b,c;
>>
>>   x=(-b + sqrt(b*b - 4*a*c)) / (2*a);
>>
>> or:
>>
>>   double x = (- double b + sqrt(b*b - 4 * double a*double c) / (2*a);
>>
>> (I know this is not C syntax but it's the same principle of mixing
>> things up that shouldn't be mixed up.)
>
> <jaw drops>  Really?  You support your argument with some made up
> syntax that has nothing to do with the case being discussed?

You can't see that both introduce clutter that is going to affect 
readability? If I'm trying to grasp an algorithm expressed by the code, 
then it's going to be easier without arbitrary declarations all over the 
place. (An int a=0; will also move that assignment 4 characters to the 
right, out of the line of the other assignments.)

>
>> Take another example:
>>
>>   point *p1 *p2, *p3;
>
> (missing ',')
>
>> Here, I don't really need to write anything further, as that
>> declaration is sufficient: those p1, p2, and p3 variables are clearly
>> related. That relationship is lost if the declarations are split up
>> because each is first used in a different place.
>
> Did anyone say that you *have* to separate related declarations?  Your
> argument seems to be against making use of the permission to delay
> declaration until first use, but no one is saying that you must do so in
> every case.

Sure, people can use either style. However if there is a possibility 
that there are other declarations buried in the code (someone decided 
they will try a p4, declare it in-place, then forgot about it) then it 
is something you have to consider.

So you see a *p3 at the top, see a p3 used in the code, and think that's 
it. Then you discover another p3 in a nested block! Possible of a 
different type too.

I think most people will use my preferred style, but an awful lot 
apparently think it's OK to declare names in arbitrary, unexpected places.

-- 
Bartc

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Do variables need to be initialized? fl <rxjwg98@gmail.com> - 2015-06-01 16:48 -0700
  Re: Do variables need to be initialized? Richard Heathfield <rjh@cpax.org.uk> - 2015-06-02 00:55 +0100
    Re: Do variables need to be initialized? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-06-01 18:22 -0600
      Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-02 08:05 -0700
        Re: Do variables need to be initialized? Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:07 -0700
          Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-07-11 16:47 -0700
            Re: Do variables need to be initialized? Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-15 07:42 -0700
      Re: Do variables need to be initialized? Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:03 -0700
  Re: Do variables need to be initialized? David Brown <david.brown@hesbynett.no> - 2015-06-02 09:15 +0200
    Re: Do variables need to be initialized? Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:09 -0700
  Re: Do variables need to be initialized? David Kleinecke <dkleinecke@gmail.com> - 2015-06-03 09:30 -0700
    Re: Do variables need to be initialized? gwowen <gwowen@gmail.com> - 2015-06-03 09:41 -0700
      Re: Do variables need to be initialized? David Kleinecke <dkleinecke@gmail.com> - 2015-06-04 10:17 -0700
        Re: Do variables need to be initialized? Stephen Sprunk <stephen@sprunk.org> - 2015-06-05 11:10 -0500
          Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-05 18:22 +0100
            Re: Do variables need to be initialized? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-06-05 20:54 -0600
              Re: Do variables need to be initialized? Ian Collins <ian-news@hotmail.com> - 2015-06-06 15:49 +1200
                Re: Do variables need to be initialized? Dr Nick <nospam-4@temporary-address.org.uk> - 2015-06-06 08:42 +0100
                Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-06 13:11 -0700
                Re: Do variables need to be initialized? Dr Nick <nospam-4@temporary-address.org.uk> - 2015-06-07 16:58 +0100
                Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-06 11:01 +0100
                Re: Do variables need to be initialized? Ian Collins <ian-news@hotmail.com> - 2015-06-07 09:07 +1200
                Re: Do variables need to be initialized? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-06-06 15:06 -0600
                Re: Do variables need to be initialized? gwowen <gwowen@gmail.com> - 2015-06-08 05:39 -0700
                Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-08 14:10 +0100
                Re: Do variables need to be initialized? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-08 14:21 +0100
                Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-08 14:34 +0100
                Re: Do variables need to be initialized? David Brown <david.brown@hesbynett.no> - 2015-06-08 16:51 +0200
                Re: Do variables need to be initialized? Richard Heathfield <rjh@cpax.org.uk> - 2015-06-08 16:15 +0100
                Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-08 17:31 +0100
                Re: Do variables need to be initialized? Ian Collins <ian-news@hotmail.com> - 2015-06-09 08:06 +1200
                Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-08 22:58 +0100
                Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-08 08:27 -0700
                Re: Do variables need to be initialized? gwowen <gwowen@gmail.com> - 2015-06-08 08:01 -0700
            Re: Do variables need to be initialized? Stephen Sprunk <stephen@sprunk.org> - 2015-06-06 11:11 -0500
              Re: Do variables need to be initialized? Bartc <bc@freeuk.com> - 2015-06-06 19:09 +0100
                Re: Do variables need to be initialized? Robert Wessel <robertwessel2@yahoo.com> - 2015-06-06 13:57 -0500
                Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-06 13:52 -0700
                Re: Do variables need to be initialized? James Kuyper <jameskuyper@verizon.net> - 2015-06-06 20:57 -0400
                Re: Do variables need to be initialized? Stephen Sprunk <stephen@sprunk.org> - 2015-06-10 14:33 -0500
          Re: Do variables need to be initialized? Keith Thompson <kst-u@mib.org> - 2015-06-05 10:56 -0700

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