On Tue, 27 Oct 2020 14:40:27 +0100, Darius Blaszyk via lazarus
<lazarus@lists.lazarus-ide.org> wrote:
>>> But this is very not a very efficient way. The best is to get the start
>>> time, get the end time and subtract.
>>>
>>> var
>>> StartTime,EndTime:TDataTime;
>>> i, answer: integer;
>>> begin
>>> StartTime:=now;
>>> for i := 0 to 999999999 do
>>> begin
>>> answer := i * answer;
>>> end;
>>> EndTime:=now;
>>> memo1.lines.add('time spent: ' + TimeToStr(EndTime-StarTime) );
>>> end;
>>>
>>> But TDateTime is not accurate at all if you are measuring short periods
>>> (milliseconds).
var
StartTime,EndTime: Int64;
i, answer: integer;
begin
answer := 1;
StartTime := GetTickCount64;
for i := 0 to 999999999 do
begin
answer := i * answer; //What does this really do?
end;
EndTime := GetTickCount64;
memo1.lines.add('ms spent: ' + IntToStr(EndTime-StartTime));
end;
Now() is an extremely bad time source since it is really only fairly
accurate to seconds. It also uses floating point so it is rounding.
Int64 holds the same bumber of bits as a double but all of it is
dedicated to the number.
--
Bo Berglund
Developer in Sweden
--
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