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random numbers

Posted on 2001-08-15
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Last Modified: 2010-04-06
ive got this code in my program
timer4.interval:=4000;
now i want to make the 4000 a random number between
12000 and 32000 how do i do it ?
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Question by:catbecks
5 Comments
 
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Accepted Solution

by:
Phoenix_s earned 400 total points
ID: 6390057
depending on what kind of granularity you require.... the process for generating the timer interval can be done a number of ways

you have a starting point at 12000 so that's a constant

the remainder is 20000 of which you need a randomized chunk



let's assume the startvalue is 12000
also let's assume you want granularity of 500 ticks

then endvalue would be 12000 + ((random(40)+1)*500)

because random(x) provides values from 0 -> (x-1)

we want 1 -> x  so we add 1 to the random before we multiply anything

let's assume you want granularity of 100 ticks

then endvalue would be 12000 + ((random(200)+1)*100)

let's assume you want granularity of 250 ticks

then endvalue would be 12000 + ((random(80)+1)*250)


let's assume you want granularity of 1000 ticks

then endvalue would be 12000 + ((random(20)+1)*1000)


does that help at all
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LVL 4

Expert Comment

by:YodaMage
ID: 6390061
var
  test : boolean;
  num  : integer;
begin
  test := false;
  Randomize;
  while not test do
  begin
    num := round((random) * 100000);
    if (num >= 12000) and (num <= 32000) then test := true;
  end;
  timer4.interval:= num;
end;

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LVL 6

Expert Comment

by:Stuart_Johnson
ID: 6391136
procedure TForm1.UpdateTimeInterval;
begin
  Randomize;
  Timer4.Interval := 12000 + Random(32000);
end;

I hope this helps,

Stu.
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LVL 1

Expert Comment

by:Phoenix_s
ID: 6391421
ah hell  if you can do it...

pass parameters to the updatetimeinterval event as below..

procedure tform1.updatetimeinterval(offset,range,granularity:integer);
begin
  randomize;
  timer4.interval := offset + ((random(range div granularity)+1)* granularity);
end;

ex of use

updatetimeinterval(12000,20000,250);  will give a timerinterval of 12000 + 250 -> 20000 in increments of 250ms

or have application-wide or unit-wide variables declared as part of a initialization sequence at startup

offset#,
range#,
granularity# : integer;

you may have multiple timers with different rules so just stick in the appropriate timer's parameters as offset0, range0, and granularity0 for timer0, and so on...

procedure tform1.updatetime#interval;
begin
  randomize;
  timer#.interval := offset# + ((random(range# div granularity#)+1)* granularity#);
end;

replacing the # with timer #'s
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LVL 9

Expert Comment

by:ITugay
ID: 6391744
Hi catbecks,

here is my version :-)

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  TTimer(Sender).Interval := 12000 + Random(32000-12000);
  //
  // rest of your code here
  //
end;

initialization
  // to avoid of the same sequences on every programm start
  Randomize;
end.
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