why so much mem?

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Fernandez Jose
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Posts: 8
Joined: Wed Sep 18, 2002 2:10 am

why so much mem?

Post by Fernandez Jose » Wed Sep 25, 2002 9:35 am

how it's possible that this code spend 320kb of memory?
program factor;
const
F7=string('5040');
F8=string('40320');
F9=string('362880');
F10=string('3628800');
F11=string('39916800');
F12=string('479001600');
F13=string('6227020800');
sOver=('Overflow!');
sUndr=('Underflow!');

var
dato:longInt;
begin
readln(dato);
while (not eof(input)) do
begin
readln(dato);
if dato<0 then begin
if dato mod 2 = 0 then writeln(sUndr) else writeLn(sOver) end
else begin
case dato of
0..6: writeLn(sUndr);
7: writeLn(F7);
8: writeLn(F8);
9: writeLn(F9);
10: writeLn(F10);
11: writeLn(F11);
12: writeLn(F12);
13: writeLn(F13);
else writeLn(sOver);
end; end;
end;
end.

I really don't understand that a 36 lines program with a single variable can be so memory greedy

Ivor
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Posts: 150
Joined: Wed Dec 26, 2001 2:00 am
Location: Tallinn, Estonia

Post by Ivor » Wed Sep 25, 2002 11:13 am

As far as I have figured it out, it has to do something with internal IO buffering. Not sure about it though.

Ivor
There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

Fernandez Jose
New poster
Posts: 8
Joined: Wed Sep 18, 2002 2:10 am

Post by Fernandez Jose » Wed Sep 25, 2002 1:22 pm

Probably you'r right. But as anyhow I realize that the same algorithm in C++ is much faster than in Pascal. The problem 264 (Count on Cantor) in Pascal uses 324kb of memory and 0.130 s. of CPU time, while in C++ the figures are 64kb for memory and 0.010 s. of time.
All that despite I don't know C or C++, appart from the basics.

Ivor
Experienced poster
Posts: 150
Joined: Wed Dec 26, 2001 2:00 am
Location: Tallinn, Estonia

Post by Ivor » Wed Sep 25, 2002 2:20 pm

Are you sure the algorithm you used is exactly the same? :roll:

I have noticed that Pascals IO is too slow -- C, C++ can almost always beat it. But I have also noticed that pascals floating point functions are slighly faster that that of C. That was true for gnu pascal, don't know about freepascal. I just noticed it when I was looking through ranklists.

Ivor
There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

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