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how do I initialize an array in an indicator that is not a buffer?

  • #1
  • First Post: Dec 1, 2009 11:12am Dec 1, 2009 11:12am
hey...need some more help...

how do I initialize an array in an indicator that is not a buffer, but it needs to hold a value for every bar on the chart?

I tried this but needless to say it doesn't work:
Inserted Code
double atr[Bars];
  • #2
  • Dec 1, 2009 11:35am Dec 1, 2009 11:35am
i always use a number......

double atr[100];

where 100 sets maximum elements.....h
to trade and code, keep both simple... no call to impress....h
  • #3
  • Edited 11:51am Dec 1, 2009 11:39am | Edited 11:51am
Quoting hayseed
i always use a number......

double atr[100];

where 100 sets maximum elements.....h
no, double atr[x], x needs to equal bars and nothing less.

I've just been doing too much coding, I can't figure out anything anymore.

hopefully someone will have answered this when I wake up.
  • #4
  • Dec 1, 2009 11:51am Dec 1, 2009 11:51am
Quoting aicccia
how do I initialize an array in an indicator that is not a buffer, but it needs to hold a value for every bar on the chart?
Inserted Code
    double atr[];
    
    ...
    ArraySetAsSeries(atr, false);
    ArrayResize(atr, Bars);
    ArraySetAsSeries(atr, true);

    ...

    atr[0] = Bid;
  • #5
  • Dec 1, 2009 11:56am Dec 1, 2009 11:56am
Quoting Irtron
Inserted Code
    double atr[];
    
    ...
    ArraySetAsSeries(atr, false);
    ArrayResize(atr, Bars);
    ArraySetAsSeries(atr, true);

    ...

    atr[0] = Bid;

wow thanks a million. seriously.
  • #6
  • Dec 1, 2009 12:06pm Dec 1, 2009 12:06pm
make sure you don't use ArrayResize() on every tick. It seems to be quite expensive, at least with large arrays (thousands of elements).
  • #7
  • Dec 1, 2009 1:04pm Dec 1, 2009 1:04pm
Quoting 7bit
make sure you don't use ArrayResize() on every tick. It seems to be quite expensive, at least with large arrays (thousands of elements).
so put the
Inserted Code
    ArraySetAsSeries(atr, false);
    ArrayResize(atr, Bars);
    ArraySetAsSeries(atr, true);

in init() ?
  • #8
  • Dec 1, 2009 1:18pm Dec 1, 2009 1:18pm
Quoting aicccia
no, double atr[x], x needs to equal bars and nothing less.
.
well in that case i'd use a big number......h
to trade and code, keep both simple... no call to impress....h
  • #9
  • Dec 1, 2009 1:37pm Dec 1, 2009 1:37pm
Quoting hayseed
well in that case i'd use a big number......h
No. Hardcoded limits, no matter how big, no matter for what, are the root of all evil in software design. Don't do it.
  • #10
  • Dec 1, 2009 2:48pm Dec 1, 2009 2:48pm
hey 7bit..... now i'm courious..... if you have the time, why.....

it seems to me best path.... by limiting the maximum number of elements to suit your specfic needs, plus a few extra's of course, you will not have the burden of data you'll never use anyway..........

similar to someone not loading a hour chart with 20 years worth of bars when they only want to see this week.....

where is the harm in limiting a buffer to 500 if all we will ever want is 20.... it seems cost effective.....

if you have the time......h

Inserted Code
 
   for(int i=0; i<500; i++)
    atr[i]
to trade and code, keep both simple... no call to impress....h
  • #11
  • Dec 1, 2009 2:57pm Dec 1, 2009 2:57pm
Quoting hayseed
where is the harm in limiting a buffer to 500 if all we will ever want is 20.... it seems cost effective.....
You dont know what will eventually be needed in the future. Just make it an external parameter and give it your 20 bars as default value.

* "640kB should be enough for everybody"
* FAT16
* FAT32 (they didn't learn!)
* Year 2000 problem
* almost every stupid bug or buffer overflow in almost any kind of software.
  • #12
  • Edited 3:23pm Dec 1, 2009 3:01pm | Edited 3:23pm
Quoting hayseed
similar to someone not loading a hour chart with 20 years worth of bars when they only want to see this week.....
You can load it with 20 years if you want. It is not limited to a week.

People have been writing software for over 60 years now. Many of them are already dead, many of them have long grey beards already (look at my avatar), but they all accumulated a great amount of wisdom during all these decades and gave it to the next generation in the form of best practices and rules to follow to avoid the mistakes they once made. Avoiding hardcoded limits is one such rule to keep trouble away.

I doubt you will be able to prove these rules wrong with a forum post in a forum where the more experienced hobby programmers help the less experienced ones.
  • #13
  • Dec 1, 2009 3:38pm Dec 1, 2009 3:38pm
Quoting 7bit
I doubt you will be able to prove these rules wrong .
such was not and never will be my intent.....
//--

//--

Quoting 7bit
with a forum post in a forum where the more experienced hobby programmers help the less experienced ones.

hear ya loud and clear....... thanks for your time......h
to trade and code, keep both simple... no call to impress....h
  • #14
  • Dec 2, 2009 4:26am Dec 2, 2009 4:26am
Quoting 7bit
make sure you don't use ArrayResize() on every tick. It seems to be quite expensive, at least with large arrays (thousands of elements).
Bars value doesn't change every tick, does it? Surely ArrayResize() wouldn't have bigger performance penalty if it resizes to the same size comparing to dedicated bit of code that checks the size separately:

Inserted Code
void start()
{
    int i, t;
    double atr[];
    
    t = GetTickCount();
    for (i = 0; i < 100000; i++)
        ArrayResize(atr, i);
    Print(GetTickCount() - t);
    
    t = GetTickCount();
    for (i = 0; i < 100000; i++)
        ArrayResize(atr, 100000);
    Print(GetTickCount() - t);

    t = GetTickCount();
    for (i = 100000; i > 0; i--)
        ArrayResize(atr, i  );
    Print(GetTickCount() - t);
}

Sixteen microseconds for 100000 calls looks more like looping overhead. The resizing itself costs nothing really.

2009.12.02 13:12:03testScript EURUSDm,M30: uninit reason 0
2009.12.02 13:12:03testScript EURUSDm,M30: 99562
2009.12.02 13:10:24testScript EURUSDm,M30: 16
2009.12.02 13:10:24testScript EURUSDm,M30: 105125
2009.12.02 13:08:39testScript EURUSDm,M30: loaded successfully
  • #15
  • Last Post: Dec 3, 2009 7:02pm Dec 3, 2009 7:02pm
Quoting 7bit
* Year 2000 problem
-- flashback-- wow Ya that was an actual real issue, at least with Foxpro, if SET CENTURY ON wasn't in the code some index sorts would be all messed up. It's probably a good idea to use a variable for the arraysize for flexibilitiy imo. and set it to some initial value.
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