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Article #338

Re: image processing loops: a c programming question

#338
From: S.P.Zeidler
Date: Wed, 26 Aug 1992 16:20
36 lines
1861 bytes
In <1992Aug13.193434.660@bmw.mayo.edu> elw@jaguar.sky2 (Ellis Workman, 1-157 Med Sci, 4-4435) writes:
>In article 713717257@isy, stefang@isy.liu.se (Stefan Gustavson) writes:
>>Or if you don't care which row you are on, you could just write:
>>  for(dp=data; dp<xsize*ysize*sizeof(int); *dp++= ...)
>		DO YOU REALLY WANT TO DO THE 
>			xsize*ysize*sizeof(int)
>			(compute byte count)
>		ON EVERY ITERATION OF THE LOOP??????
>how about
>			for(i=xsize*ysize, dp = data;i;i--)
>				*dp++ = ...;
Uhmn, that would not be the greatest problem regarding that code;
probably intended was:
{
int xsize, ysize;
int data[ysize][xsize], *dp, *dpmax;

for (dp=data, dpmax=data+xsize*ysize; dp<dpmax; dp++) *dp = foobar+stuff;

/* I like to do the increment in the for () 'cause that ensures
   defined behaviour with nested if() in the loop and generally
   reads better (IMHO) */
}
Note the absence of the sizeof and the presence of data in the
max-data-ptr you check against.

Sorry if that followup strikes you as a bit late; we are still lagging
a lot, but it's getting better ;-)

regards,
	spz
-- 
        spz is S.Petra Zeidler  Copyright 1992 S.Petra Zeidler
spz@specklec.mpifr-bonn.mpg.de  
 MPI fuer Radioastronomie Bonn  
    Auf dem Huegel 69, Germany  reading prescription: cum kilo salis
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References: <stefang.713717257@isy> <1992Aug13.193434.660@bmw.mayo.edu>

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From: spz@specklec.mpifr-bonn.mpg.de (S.P.Zeidler)
Subject: Re: image processing loops: a c programming question
Message-ID: <1992Aug26.162058.1633@mpifr-bonn.mpg.de>
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References: <stefang.713717257@isy> <1992Aug13.193434.660@bmw.mayo.edu>
Date: Wed, 26 Aug 1992 16:20:58 GMT
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