Re: basic static variables question

From:
pauldepstein@att.net
Newsgroups:
comp.lang.c++
Date:
Tue, 20 Nov 2007 05:43:10 -0800 (PST)
Message-ID:
<17a50d1b-9afa-4be6-af5a-5ab55b59c7ca@d21g2000prf.googlegroups.com>
On Nov 19, 10:41 pm, Joel Yliluoma <bisq...@iki.fi> wrote:

On Mon, 19 Nov 2007 01:03:29 -0800 (PST), pauldepst...@att.net wrote:

On Nov 19, 4:55 pm, Sohail Somani <soh...@taggedtype.net> wrote:

On Mon, 19 Nov 2007 00:44:46 -0800, pauldepstein wrote:

I have code that looks like this:

for (int counter = 0; counter < 100; ++ counter) {
  { static int blah = 0;
   if (blah == 0)
   // do something;
    blah ++;
     }
}

This is already legal code. My problem is that I want it to execute the
inner loop 100 times.


There is no inner loop. Only a single loop. Is that what you meant to
post?


Thanks a lot for following up. The code posted is as intended. There
is one block ( hence the { } ) inside the for loop. I was
carelessly calling the inner block a loop. I want it to do what's in
the inner block exactly once for each value of the counter.


You mean, when you issue the loop multiple times, it will invoke
the particular code only once for each distinct value of the loop?

I.e.
  for(int c=0; c<10; ++c)
    for(int a=0; a<10; ++a)
      for(int b=5; b < 5+a; ++b)
      {
        if(something here)
          std::cout << b << ',';
      }
  This would output 5,6,7,8,9,10,11,12,13, and nothing else?

You can try something like this:
  for(int c=0; c<10; ++c)
    for(int a=0; a<10; ++a)
      for(int b=5; b < 5+a; ++b)
      {
        static std::set<int> seen;
        if(seen.find(b) == seen.end())
        {
          seen.insert(b);
          std::cout << b << ',';
        }
      }
Instead of std::set<>, you can use some other data structure
that fits your purpose better if you are so inclined.

--
Joel Yliluoma -http://iki.fi/bisqwit/- Hide quoted text -

- Show quoted text -


Thanks for trying to help. I was puzzled as to why a piece of code
didn't work. The intended result was to display a column of data
(call it DATA) which depended on a different set of excel inputs (call
this INPUTS) The intended result was that DATA depended only on
INPUTS. However, each time I hit shift F9 to recalculate XL, DATA
changed even though the INPUTS were clearly constant. But my guesses
as to the reason for the bug were way off at the time of the posting.
I had wrongly assumed that I had introduced the bug. In fact one of
the functions that I used had a bug. I had naively trusted it but
this previous legacy function doesn't work properly at all. The
mistake was to place too much trust in the prior code. By overly
trusting the prior code, I was reduced to desperately bad logic to try
and explain the mysterious errors (as Julia pointed out.) She said it
very well -- "Events don't just jump right in the middle of your
code."

Paul Epstein

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