OnCalculate() Copying from the rates arrays

[Ian Venner]

I need to copy the last ten highs from the high[] array in OnCalculate()

   int Length = 10;
   double ahigh[];
   ArrayResize(ahigh,Length);
   ArrayCopy(ahigh,high,0,0,Length);
   for(int i=0; i<Length; i++)
   {
    Print("high[",i,"] = ",high[i]," ahigh[",i,"] = ",ahigh[i]);
   }
   int compare = ArrayCompare(high,ahigh,0,0,Length);
   Print("ArrayCompare = ",compare);

When I print them it looks ok but ArrayCompare() returns -1 why would that be ?

ArrayCompare = -1
high[9] = 1.3748 ahigh[9] = 1.3748
high[8] = 1.3811 ahigh[8] = 1.3811
high[7] = 1.3861 ahigh[7] = 1.3861
high[6] = 1.3898 ahigh[6] = 1.3898
high[5] = 1.3905 ahigh[5] = 1.3905
high[4] = 1.3862 ahigh[4] = 1.3862
high[3] = 1.3833 ahigh[3] = 1.3833
high[2] = 1.385 ahigh[2] = 1.385
high[1] = 1.3864 ahigh[1] = 1.3864
high[0] = 1.3822 ahigh[0] = 1.3822

Also if I call a value from the spread[] array,

Print(spread[0]);

I get array out of range error in the experts log.

[Shui Wang]

(after 4 years now...呵呵)      i'm also troubled by this error...until i realized that the "spread[]" array may not be populized by MT4.

you can see this by:

Print(ArraySize(spread));

[William Roeder]

There is a difference between the arrays passed to OnCalculate (e.g. low[]) and the predefined variables (e.g. Low[].) The predefined variables are all ordered AsSeries. The passed arrays have no default direction.

To determine the indexing direction of time[], open[], high[], low[], close[], tick_volume[], volume[] and spread[], call ArrayGetAsSeries(). In order not to depend on default values, you should unconditionally call the ArraySetAsSeries() function for those arrays, which are expected to work with.
          Event Handling Functions - Functions - Language Basics - MQL4 Reference

[Florin Ionescu]

As I see it,

Bad decision to let those arrays passed to OnCalculate() be whatever

Those arrays should've have AsSeries = 1

It only brings unnecessary confusion.
Makes you wonder why the need for AsSeries in the first place,

but

...whatever