Fixing an Array out of range error in MT4 EA | Forex Factory

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Fixing an Array out of range error in MT4 EA

  • #1
  • First Post: Edited 4:57am Oct 10, 2019 3:37am | Edited 4:57am
I made an EA with the following...

extern int IntIndTF1 = 4;
extern int IntInd1S1 = 2;
extern int IntInd1S2 = 14;

extern int IntIndTF2 = 1;
extern int IntInd2S1 = 3;
extern int IntInd2S2 = 9;
Inserted Code
PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,IntInd1S1)];
PerL1 = Low[iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,IntInd1S1)];
PerM1 = NormalizeDouble((PerH1+PerL1)/2,Digits);
 
PerH2 = High[iHighest(SymbolToManage,IntIndTF2,MODE_HIGH,IntInd2S2,IntInd2S1)];
PerL2 = Low[iLowest(SymbolToManage,IntIndTF2,MODE_LOW,IntInd2S2,IntInd2S1)];
PerM2 = NormalizeDouble((PerH2+PerL2)/2,Digits);

It worked great until I started testing other symbols with it, then came the dreaded Array out of range error, so I changed it to this...
Inserted Code
int BarCount = Bars;
if (BarCount < 1) BarCount = 1;
for (int i=0; i>Bars; i--) {
PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,i+IntInd1S1)];
PerL1 = Low[iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,i+IntInd1S1)];
PerM1 = NormalizeDouble((PerH1+PerL1)/2,Digits);
 
PerH2 = High[iHighest(SymbolToManage,IntIndTF2,MODE_HIGH,IntInd2S2,i+IntInd2S1)];
PerL2 = Low[iLowest(SymbolToManage,IntIndTF2,MODE_LOW,IntInd2S2,i+IntInd2S1)];
PerM2 = NormalizeDouble((PerH2+PerL2)/2,Digits);
}
The array out of range errors appears to have diminished. HOWEVER, now I can not get it to simulate the previous settings which were doing well...

extern int IntIndTF1 = 4;
extern int IntInd1S1 = 2;
extern int IntInd1S2 = 14;

extern int IntIndTF2 = 1;
extern int IntInd2S1 = 3;
extern int IntInd2S2 = 9;

I've tested +1 and -1 ranges but the EA is now not returning to the same calculated values for the same bars. How can I change the code to eliminate the errors yet maintain the previously tested values and results.

This is in a EA not using an indicator. The values for the HHLLs are in the EA itself. I want it to be able to read and get the same results for the extern variable on the bar that triggers the signal.
  • #2
  • Edited 6:36am Oct 10, 2019 5:49am | Edited 6:36am
Quoting Pipologist
I made an EA with the following... extern int IntIndTF1 = 4; extern int IntInd1S1 = 2; extern int IntInd1S2 = 14; extern int IntIndTF2 = 1; extern int IntInd2S1 = 3; extern int IntInd2S2 = 9; PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,IntInd1S1)]; PerL1 = Low[iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,IntInd1S1)]; PerM1 = NormalizeDouble((PerH1+PerL1)/2,Digits); PerH2 = High[iHighest(SymbolToManage,IntIndTF2,MODE_HIGH,IntInd2S2,IntInd2S1)]; PerL2 = Low[iLowest(SymbolToManage,IntIndTF2,MODE_LOW,IntInd2S2,IntInd2S1)];...
Try fixing your for loop first, in the second code block, the loop never runs so no errors could happen: i=0 but checks i>Bars. With i decrementing should be:
for(int i=Bars-IndicatorCounted()-1;i>0;i—)
  • #3
  • Oct 10, 2019 8:33am Oct 10, 2019 8:33am
Quoting Beerrun
{quote} Try fixing your for loop first, in the second code block, the loop never runs so no errors could happen: i=0 but checks i>Bars. With i decrementing should be: for(int i=Bars-IndicatorCounted()-1;i>0;i—)
The code is inside an ea only, not an indicator will IndicatorCounted() still work inside an ea?
  • #4
  • Oct 10, 2019 9:08am Oct 10, 2019 9:08am
Quoting Pipologist
{quote} The code is inside an ea only, not an indicator will IndicatorCounted() still work inside an ea?
Yeah it should work. If not then create a variable to keep a running count. Otherwise it is going to run the loop for every bar on every tick.
  • #5
  • Oct 10, 2019 9:48am Oct 10, 2019 9:48am
Quoting Beerrun
{quote} Yeah it should work. If not then create a variable to keep a running count. Otherwise it is going to run the loop for every bar on every tick.
This is what I did...
Inserted Code
int counted_bars=IndicatorCounted();
for(int i=Bars-counted_bars-1;i>0;i--) {
etc. etc. etc.
}

It seems like it may have taken care of the array out of range, I need to check other symbols to test. However, a test by tick was taking forever. So I reviewed when and where this code is being called and took it out of the top section of void OnInit and put it after
Inserted Code
static datetime prevtime = Time[0];
if (prevtime == Time[0]) return;
prevtime = Time[0];
which I have near the bottom of OnInit

It didn't need to be checked tick by tick, just by bar, whereas other parts of the exit strategy require tick by tick monitoring.

I think it should work now. I have to check it against other symbols that were giving me the problem, but taking the code out of tick by tick checking makes it run much faster of course.
  • #6
  • Oct 10, 2019 10:00am Oct 10, 2019 10:00am
Well, I'm still getting "array out of range" errors on other symbols during tests with this. Placing it out of tick by tick checking make it faster is a plus but it doesn't solve the original issue. Back to wrestling it.
Inserted Code
int counted_bars=IndicatorCounted();
for(int i=Bars-counted_bars-1;i>0;i--) {
PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,IntInd1S1)];
PerL1 = Low[iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,IntInd1S1)];
PerM1 = NormalizeDouble((PerH1+PerL1)/2,Digits);
PerH2 = High[iHighest(SymbolToManage,IntIndTF2,MODE_HIGH,IntInd2S2,IntInd2S1)];
PerL2 = Low[iLowest(SymbolToManage,IntIndTF2,MODE_LOW,IntInd2S2,IntInd2S1)];
PerM2 = NormalizeDouble((PerH2+PerL2)/2,Digits);
}
  • #7
  • Oct 10, 2019 10:39am Oct 10, 2019 10:39am
I've managed to get the variables to pass though and simulate the previous results very closely with this...
Inserted Code
int counted_bars=Bars-MathMax(MathMax(IntInd1S2,IntInd2S2),MathMax(IntInd1S1,IntInd2S1));
for(int i=Bars-counted_bars-1;i>0;i--) {
PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,i+IntInd1S1)];
PerL1 = Low[iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,i+IntInd1S1)];
PerM1 = NormalizeDouble((PerH1+PerL1)/2,Digits);
PerH2 = High[iHighest(SymbolToManage,IntIndTF2,MODE_HIGH,IntInd2S2,i+IntInd2S1)];
PerL2 = Low[iLowest(SymbolToManage,IntIndTF2,MODE_LOW,IntInd2S2,i+IntInd2S1)];
PerM2 = NormalizeDouble((PerH2+PerL2)/2,Digits);

IntInd1S2,i+IntInd1S1 were previously set at 2 and 14 and now work at 1 and 13 which makes sense.

Still getting array out of range errors though.
  • #8
  • Edited 8:59pm Oct 10, 2019 11:25am | Edited 8:59pm
Quoting Pipologist
Well, I'm still getting "array out of range" errors on other symbols during tests with this. Placing it out of tick by tick checking make it faster is a plus but it doesn't solve the original issue. Back to wrestling it.
Perhaps use the Bars() function which takes the symbol and timeframe as parameters, instead of the Bars variable which is limited to the current chart symbol and timeframe.
An extra thing to consider is if iLowest/Highest returns an error, you’d be doing Low[-1]
  • #9
  • Oct 10, 2019 7:34pm Oct 10, 2019 7:34pm
Quoting Pipologist
I've managed to get the variables to pass though and simulate the previous results very closely with this... int counted_bars=Bars-MathMax(MathMax(IntInd1S2,IntInd2S2),MathMax(IntInd1S1,IntInd2S1)); for(int i=Bars-counted_bars-1;i>0;i--) { PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,i+IntInd1S1)]; PerL1 = Low[iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,i+IntInd1S1)]; PerM1 = NormalizeDouble((PerH1+PerL1)/2,Digits); PerH2 = High[iHighest(SymbolToManage,IntIndTF2,MODE_HIGH,IntInd2S2,i+IntInd2S1)]; PerL2 = Low[iLowest(SymbolToManage,IntIndTF2,MODE_LOW,IntInd2S2,i+IntInd2S1)];...
Are you sure you are getting the error from the above? Because this is not filling any arrays, it just assigns the value of the last i to the doubles and does unnecessary cycles. Hi!

ofc it might hit some High or Low out of range. For that just set the ea to run after the 17th bar.
  • #10
  • Oct 11, 2019 3:11am Oct 11, 2019 3:11am
Yeah that was a copy and paste error above.

Not sure I understand the run after the 17th bar concept and how to implement that or why it works.

For the meantime, I've settled with this...repeated a second time with a second set of variables for the second indicator within the ea. The bars with time shift mentioned by Beerrun made the testing more controlled and less to the whim of the MT4 compiler since it is testing for any TF but put on a 4hour chart. Eventually I want the ea to run the same with the same results regardless of the TF chart it's on. I think reading TFs from Bars() is part of the solution. The array out of range error, is still an issue, what is the significance of the 17th bar and how do you get the ea to run after the 17th bar?
Inserted Code
int BarCount1;
int TFBars1 = Bars(SymbolToManage,IntIndTF1);
int BarsCounted1 = TFBars1-MathMax(IntInd1S2,IntInd1S1+1);
if (BarsCounted1 < 0) {return;}
int LimitBars1 = TFBars1-BarsCounted1;
for (BarCount1 = LimitBars1; BarCount1 >= 0; BarCount1--) {
PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,BarCount1+IntInd1S1)];
etc...
}
  • #11
  • Edited 5:57am Oct 11, 2019 5:40am | Edited 5:57am
Quoting Pipologist
Yeah that was a copy and paste error above. Not sure I understand the run after the 17th bar concept and how to implement that or why it works. For the meantime, I've settled with this...repeated a second time with a second set of variables for the second indicator within the ea. The bars with time shift mentioned by Beerrun made the testing more controlled and less to the whim of the MT4 compiler since it is testing for any TF but put on a 4hour chart. Eventually I want the ea to run the same with the same results regardless of the TF chart it's...
Don’t forget the (-1) to convert from size to position
BarCount1=LimitBars1-1
and make sure iLowest/iHighest is not returning -1
  • #12
  • Oct 11, 2019 6:57am Oct 11, 2019 6:57am
I added the -1 to the limit bars count and it seems to work without affecting any changes to the results so that's fine.

To make sure iLowest/iHigheset is not returning -1 I did this, pretty sure it's not the correct way b/c the results are terrible...

Inserted Code
int BarsCounted1 = TFBars1-MathMax(IntInd1S2,IntInd1S1+1);
if (BarsCounted1 < 0) {return;}
int LimitBars1 = TFBars1-BarsCounted1;
for (BarCount1 = LimitBars1-1; BarCount1 >= 0; BarCount1--) {
if ((iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,BarCount1+IntInd1S1) < 0) || (iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,BarCount1+IntInd1S1) < 0)) return;
if ((iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,BarCount1+IntInd1S1) > -1) && (iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,BarCount1+IntInd1S1) > -1)) continue;
PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,BarCount1+IntInd1S1)];
PerL1 = Low[iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,BarCount1+IntInd1S1)];
//PerM1 = NormalizeDouble((PerH1+PerL1)/2,Digits);
}
  • #13
  • Edited 8:19am Oct 11, 2019 7:04am | Edited 8:19am
Quoting Pipologist
I added the -1 to the limit bars count and it seems to work without affecting any changes to the results so that's fine. To make sure iLowest/iHigheset is not returning -1 I did this, pretty sure it's not the correct way b/c the results are terrible... int BarsCounted1 = TFBars1-MathMax(IntInd1S2,IntInd1S1+1); if (BarsCounted1 < 0) {return;} int LimitBars1 = TFBars1-BarsCounted1; for (BarCount1 = LimitBars1-1; BarCount1 >= 0; BarCount1--) { if ((iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,BarCount1+IntInd1S1) < 0) || (iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,BarCount1+IntInd1S1)...
I was thinking something like this
Inserted Code
for(int i=(IndicatorCounted()==0)?Bars(symbol,tf)-1-MathMax(IntInd1S2,IntInd1S1+1):1;i>0;i—){
 
int hi=iHighest(symbol,tf,mode,IntInd1S2,i);
if(hi!=-1)PerH1=High[hi];
else PerH1=-1;
 
int lo=iLowest(...);
if(lo!=-1)PerL1=Low[lo];
else PerL1=-1;}
  • #14
  • Oct 11, 2019 7:34am Oct 11, 2019 7:34am
Quoting Pipologist
Yeah that was a copy and paste error above. Not sure I understand the run after the 17th bar concept and how to implement that or why it works. For the meantime, I've settled with this...repeated a second time with a second set of variables for the second indicator within the ea. The bars with time shift mentioned by Beerrun made the testing more controlled and less to the whim of the MT4 compiler since it is testing for any TF but put on a 4hour chart. Eventually I want the ea to run the same with the same results regardless of the TF chart it's...
IntInd1S2,IntInd1S1
PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,BarCount1+IntInd1S1)
start at 2 bars back + barcount1, count 14 bars back = barcount1+2+14 bars+0 bar = minimum 17, so if tester starts at bar 0+barcount1 it will drop array out of range in the first 16+barcount1 bars (not in live)

if (iBars(_Symbol, PERIOD_CURRENT) >= 17 + BarCount1) { Execute my code }
  • #15
  • Oct 11, 2019 8:37am Oct 11, 2019 8:37am
Put in the minimum bar count filter like this. Seems to work well so far...back to more testing although it's sitting live on my local machine waiting to see if there is one last Friday trade to take.

int BarCount1;
int TFBars1 = Bars(SymbolToManage,IntIndTF1);
int BarsCounted1 = TFBars1-MathMax(IntInd1S2,IntInd1S1+1);
if (BarsCounted1 < 0) {return;}
int LimitBars1 = TFBars1-BarsCounted1;
for (BarCount1 = LimitBars1-1; BarCount1 >= 0; BarCount1--) {
if (iBars(SymbolToManage, IntIndTF1) >= BarCount1+IntInd1S1+IntInd1S2+2) {
PerH1 = High[iHighest(SymbolToManage,IntIndTF1,MODE_HIGH,IntInd1S2,BarCount1+IntInd1S1)];
PerL1 = Low[iLowest(SymbolToManage,IntIndTF1,MODE_LOW,IntInd1S2,BarCount1+IntInd1S1)];
}
}
  • #16
  • Oct 11, 2019 8:40am Oct 11, 2019 8:40am
Doing this leads to more questions...Can Bars() and iBars() be used interchangeably and get the same results? What is the difference?

On the tests I used both interchangeably and got the same test result but what is the difference to the compiler?
  • #17
  • Oct 11, 2019 9:02am Oct 11, 2019 9:02am
Quoting Pipologist
Doing this leads to more questions...Can Bars() and iBars() be used interchangeably and get the same results? What is the difference? On the tests I used both interchangeably and got the same test result but what is the difference to the compiler?
Just old and new mql4 changes, both work for what you want. But Bars(...) also has a 2nd version that allows start and end dates
  • #18
  • Oct 11, 2019 9:03am Oct 11, 2019 9:03am
Quoting sakisf
{quote}...so if tester starts at bar 0+barcount1 it will drop array out of range in the first 16+barcount1 bars (not in live) if ...{ Execute my code }
Are you saying to not use the filter live? Or, that the filter doesn't matter live? Would having the filter on a live ea, affect it adversely?

if (iBars(SymbolToManage, IntIndTF1) >= BarCount1+IntInd1S1+IntInd1S2+2)
  • #19
  • Oct 12, 2019 10:19am Oct 12, 2019 10:19am
Quoting Pipologist
{quote} Are you saying to not use the filter live? Or, that the filter doesn't matter live? Would having the filter on a live ea, affect it adversely? if (iBars(SymbolToManage, IntIndTF1) >= BarCount1+IntInd1S1+IntInd1S2+2)
Yes it wouldn't matter on live as you already have bars on the chart while tester recreates from 1st bar. Unless you still run it inside the for loop every tick and it checks from 1st bar in the chart.
  • #20
  • Last Post: Edited Oct 18, 2019 12:02am Oct 17, 2019 11:31pm | Edited Oct 18, 2019 12:02am
I've put aside the array out of range error for now since I've went live with this and am not currently optimizing for other symbols.

However, now I'm having the live EA take additional trades or miss trades compared to the tester (both are on real servers, not demo servers).

Below is the code I'm using for the indi calc. The indi is in the EA itself not as a separate indicator file.

Question... Would the code used below cause the calculations for PerH and PerL to shift or "repaint"? For now it's the only thing I can think of that would cause differences in trades triggered.

A little background...The EA is on a 4H chart, but TF below is set at PERIOD_M5 and IndS1 is set at 0 in the global variables. Although it's on a 4H chart looking at 5min data with a shift of 0 or 0+1, it's designed to trade only at 4H bar open which would also be at the open for the calculated 5min bars as well so it shouldn't make that much of a difference.

Here are portions of the actual code in the live EA. Luckily for now the EA has taken additional winning trades and avoided a losing trade compared to the tester, but it's important to know why and I have feeling the array calculations for PerH and PerL below may have something to do with it.

This is the code in question, and some of the surrounding code that uses it below...

BarCount;
TFBars = Bars(Symbol,TF);
BarsCounted = TFBars-MathMax(IndS2,IndS1+1);
if (BarsCounted < 0) {return;}
LimitBars = TFBars-BarsCounted;
for (BarCount = LimitBars-1; BarCount >= 0; BarCount--) {
if (iBars(Symbol,TF) >= BarCount+IndS1+Ind1S2+2) {
PerH = High[iHighest(Symbol,TF,MODE_HIGH,IndS2,BarCount+IndS1)];
PerL = Low[iLowest(Symbol,TF,MODE_LOW,IndS2,BarCount+IndS1)];
}
}


Inserted Code
 
// global settings
 
extern int TF = 2;
extern int IndS1 = 0;
 
///////////////////////////////////////////////////////////////
 
void OnInit() {
return;
}
 
void OnTick() {
 
//////////////////misc code up here////////////////////
 
if (TF == 2) TF = PERIOD_M5;
 
BarCount;
TFBars = Bars(Symbol,TF);
BarsCounted = TFBars-MathMax(IndS2,IndS1+1);
if (BarsCounted < 0) {return;}
LimitBars = TFBars-BarsCounted;
for (BarCount = LimitBars-1; BarCount >= 0; BarCount--) {
if (iBars(Symbol,TF) >= BarCount+IndS1+Ind1S2+2) {
[b]PerH[/b] = High[iHighest(Symbol,TF,MODE_HIGH,IndS2,BarCount+IndS1)];
[b]PerL[/b] = Low[iLowest(Symbol,TF,MODE_LOW,IndS2,BarCount+IndS1)];
}
}
 
// GOES TO CHECK ONCE PER BAR FROM HERE INSTEAD OF EVERY TICK
 
static datetime PrevBarTime = Time[1];
if (PrevBarTime >= Time[0]) return;
if (TimeCurrent() > (Time[0] + 45)) return;
PrevBarTime = Time[0];
 
CheckForExits();
 
LookForEntries();
 
return;}


There are no other indicator calculations used and no standard or iCustom 'indicators' used.

One other possibility I could think of is that the live server possibly has an additional 45 seconds to calculate and take the trade based on

if (TimeCurrent() > (Time[0] + 45)) return;

But the tester would not recognize the 45 second cushion and only take it at the exact simulated Time[0]. Is this a valid hypothesis?

Still am curious to know if the Bar Counting code could be leading to the "indi" shifting and repainting.

Anyone have any ideas?
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