Writing and reading integers to and from disk is fast. Writing 1.5 mil integers
takes under a ms on a test here.
Sample play …
Var
Writecount : integer;
ArrJBird : array of integer;
fStream : TFilestream;
dtstart, dtEnd : TDateTime;
begin
randomize;
setLength(ArrJBird, 1500000);
for i:=0 to 1500000-1 do ArrJBird[i] := random(1000);
dtstart := Now;
fStream := TFileStream.Create('c:\temp\myFileOfInts.txt',fmCreate);
fStream.Seek(0,soFromBeginning);
writeCount := sizeof(integer)*1500000;
fStream.Write(ArrJBird[0], writeCount);
showmessage('101st int='+inttostr(arrJBird[101]));
fStream.Destroy;
Application.ProcessMessages;
for i:=0 to 1500000-1 do ArrJBird[i] :=-1;
fStream := TFileStream.Create('c:\temp\myFileOfInts.txt',fmOpenRead);
fStream.Seek(0,soFromBeginning);
fStream.read(ArrJBird[0],writeCount);
showmessage('101st int='+inttostr(ArrJBird[101]));
dtEnd := now;
showmessage('write to and read from time: '+FloatToStr(dtEnd - dtStart));
// cleanup;
From: [email protected]
[mailto:[email protected]] On Behalf Of John Bird
Sent: Monday, 7 July 2014 8:35 p.m.
To: NZ Borland Developers Group - Delphi List
Subject: [DUG] Saving aray
I have a program that builds a very large array (over 1,500,000) of integers,
and the calculation to fill the array takes quite a while – around 40-50 secs.
If there is a quick way to do it, I would save the array to disk if it was
faster than recalculating it the next time.
I am guessing that writing the elements to strings and using CSV etc would be
quite slow, as it involves quite a lot of processing. I will run a test to
see.
Is there any really fast way to save such an array to disk? The numbers range
between 0 and 256 if that helps.
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