Attachments: Find-the-Bug

Find-the-Bug

#1
First Post: Aug 12, 2016 7:06am Aug 12, 2016 7:06am

cdeleeuw
| Joined Nov 2012 | Status: Trader | 12 Posts

FFF (ForexFactoryFriends), I couldnt trace the following bug or articles on the FFF (FF Forum);

In MT4 code I plot several graphical objects on the chart which sometimes behave unexpected.
Directly after the Start(); function the indicator checks whether a new bar is started, otherwise a Return(0) follows.

At certain new bars I plot graphical objects on the chart window, for instance the hour indication.
This should be done once and only at the 1st tick of the new bar.

After this tick the bar is started and in progress during the time frame period.
I use a well known NewBar function to detect a new bar, if (!bIsNewBar()) return(0);

At initializing MetaTrader4 this works correctly for the whole history, but then during new formed bars the object is often plotted several times, almost on the same position and mostly slightly below each other, 2,3,4 times.

In a 3GL (3rd Generation Language like Fortran, C, Pascal, Cobol) this is impossible, it does what you program.
MT4 is a 3GL (C) with a 4GL overlay for a lot of Forex, time and graphical functions.

Is this a bug in my program or something in MT4 and to work around it ?
I suppose this problem is tackled several times, but I couldnt find a thread.

See a screenshot and my MT4 code example (which could be much shorter using iterations, but OK).
It plots vertical hour lines, hour values and at every quarter of a day == indications on 10-pip distances for this quarter and below <- for the remainer.
Here is where you'll find the unexpected extra plots.

Thanks for support, Ill close this thread with the correct solution and MT4 source code.

(My background is white, my toner supplier hates me. Always upload mt4 sources code in stead of ex4 only).

Cheers, cdeleeuw

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#-TimeMarks-GMT.mq4 31 KB | 349 downloads

#2
Aug 12, 2016 8:03am Aug 12, 2016 8:03am

Gorraf
Joined Aug 2016 | Status: Trader | 125 Posts

Not really related to the bug, but, since there is only 60 minutes in an hour, shouldn't be the multiplier in line 130, Col 26 be 60?
(Which would change of course a lot of other things as well.)

#3
Aug 12, 2016 8:31am Aug 12, 2016 8:31am

cdeleeuw
| Joined Nov 2012 | Status: Trader | 12 Posts

Thanks Gorraf for screening the code.
It was my clumsy way to translate f.i. 15 Hours and 30 Minutes to the integer value 15*100 + 30*1 = 1530, without searching for the available MT4 internal Time Functions first.
Cheers cdeleeuw

#4
Aug 14, 2016 6:47am Aug 14, 2016 6:47am

cdeleeuw
| Joined Nov 2012 | Status: Trader | 12 Posts

Somewhat more explanation on my previous question about the repeated plot of the same graphical object during the start of a new bar in live situations;

In backtesting and scanning the history of a live connection only completed bars are processed.
The problem occurs directly after live ticks follow and start building new bars.

The NewBar function in my indicator determines when a new tick is beyond the timeframe of the last bar and a new bar must start.
Otherwise a return out of the Start() segment follows and no plot of a graphical object will be drawn until the 1st tick of the next bar.

This 1st tick may fall one or several seconds after the round server clock, for instance at 14:00:02 in stead of 14:00:00.
It is the incoming tick which initiates every Start() function where a new bar is formed, but then with the round server time for the Open.

Furthermore, within a single second of the initiating tick, one or more ticks may follow and the NewBar function returns TRUE once, and then sets prevtime, which should prevent a repeated execution of Start() within the same bar.

Still the complete Start() function seems to be executed again and the same object will repeatedly be plotted, with slightly different price levels and below or above the precious one.

What is the explanation of the repeated plot of objects, sometimes 3-4 times and quite often ?
I don’t receive several ticks in a split second as much as I see multiple plots so often.

What is the problem, what causes the ´bug´, how to avoid this ?

Cheers, cdeleeuw

#5
Aug 14, 2016 7:30am Aug 14, 2016 7:30am

cyber1
Joined Jan 2011 | Status: Trader | 1,299 Posts

Quoting cdeleeuw

Disliked

FFF (ForexFactoryFriends), I couldnt trace the following bug or articles on the FFF (FF Forum); In MT4 code I plot several graphical objects on the chart which sometimes behave unexpected. Directly after the Start(); function the indicator checks whether a new bar is started, otherwise a Return(0) follows. At certain new bars I plot graphical objects on the chart window, for instance the hour indication. This should be done once and only at the 1st tick of the new bar. After this tick the bar is started and in progress during the time frame period....

Ignored

cdeleeuw-
It's not a bug. When you plot an object and you later want to update the object and maybe move to a new location you must first either delete it or move it. I will show you several examples of how this can be done.

Also I notice your utilization of the ObjectsDeleteAll() function which is very bad practice. It not only deletes all the objects created by this indicator but any other object by any other indicator or hand-drawn objects.

First you should define variable string ID to attach to each object as a prefix in the name of the object.
string ID = "TMK_"
Then instead of using ObjectsDeleteAll() you need a delete function.

Inserted Code

//+------------------------------------------------------------------+
//                                                                   +
//+------------------------------------------------------------------+
void DeleteObjects(string label){
   int objs = ObjectsTotal();
   string name;
   for(int cnt=ObjectsTotal()-1;cnt>=0;cnt--){
  
      name=ObjectName(cnt);
      if (StringFind(name,label,0)>-1) ObjectDelete(name);
      WindowRedraw();
   }
  
 return;
}

then on DeInit() call with one parameter DeleteObjects(ID)
The following are three examples of how you can avoid the problem you are having.

Inserted Code

   string sObjName = ID+"trades3";
   if (ObjectFind(sObjName) == -1) {
    ObjectCreate(sObjName, OBJ_LABEL, 0, 0, 0);
  }
  }  }
  ObjectSet(sObjName, OBJPROP_XDISTANCE, XPos2);
  ObjectSet(sObjName, OBJPROP_YDISTANCE, YPos2+20);
  ObjectSetText(sObjName, OpenTrades3, HeadrFntSize, HeadrFnt,HeaderFntColor);
  ObjectSet(sObjName, OBJPROP_CORNER, WhichCorner);
 
  string sObjName = ID+"trades3";
 if (StringFind(sObjName,ID,0)>-1) ObjectDelete(sObjName);
  ObjectCreate(sObjName, OBJ_TREND,0,Time[1],lastopen,Time[smallesthit], Close[smallesthit]);
  ObjectSet(sObjName, OBJPROP_COLOR, LineClr);
  ObjectSet(sObjName, OBJPROP_WIDTH, 2);
  ObjectSet(sObjName, OBJPROP_STYLE, STYLE_SOLID);
  ObjectSet(sObjName, OBJPROP_RAY, TRUE);
  
  string sObjName = ID+"trades3";
  ObjectDelete(sObjName);
  ObjectCreate(sObjName, OBJ_TREND,0,Time[1],lastopen,Time[smallesthit], Close[smallesthit]);
  ObjectSet(sObjName, OBJPROP_COLOR, LineClr);
  ObjectSet(sObjName, OBJPROP_WIDTH, 2);
  ObjectSet(sObjName, OBJPROP_STYLE, STYLE_SOLID);
  ObjectSet(sObjName, OBJPROP_RAY, TRUE);

You can also try the ObjectMove() function
https://docs.mql4.com/objects/objectmove

#6
Aug 14, 2016 9:07am Aug 14, 2016 9:07am

cdeleeuw
| Joined Nov 2012 | Status: Trader | 12 Posts

Thanks cyber1 for the fast response and examples !

I was aware of the ObjectsDeleteAll problem, but the TimeMarks-GMT indicator still was a v0.1 version to be completed.
Your Delete Function does the job even better.
I’m not an experienced MT4 programmer and will gladly experiment with your suggested examples.

Still an addition to my question;

My intention was not to delete or move these objects.
They are supposed to be fixed time marks per hour with some extra info per quarter-day and without further adjustments.

I expected that the IsNewBar function would prevent that the same object will be plotted on the same bar repeatedly.
Which is not the case in live connection and after processing the history first before the ticks enter.
I use IsNewBar often in other EA’s and Indicators and noticed no problems yet (?).

Therefore I’m much interested in the reason what is going wrong here and what I still don’t understand.

Cheers cdeleeuw

#7
Last Post: Aug 14, 2016 8:22pm Aug 14, 2016 8:22pm

cyber1
Joined Jan 2011 | Status: Trader | 1,299 Posts

Quoting cdeleeuw

Disliked

Thanks cyber1 for the fast response and examples ! I was aware of the ObjectsDeleteAll problem, but the TimeMarks-GMT indicator still was a v0.1 version to be completed. Your Delete Function does the job even better. Im not an experienced MT4 programmer and will gladly experiment with your suggested examples. Still an addition to my question; My intention was not to delete or move these objects. They are supposed to be fixed time marks per hour with some extra info per quarter-day and without further adjustments. I expected that the IsNewBar function...

Ignored

cdeleeuw-
It appears you have the object name tied to either Bar number or Bar time. Correcting this should solve your problem.

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