Experts: MQL5 Programming for Traders – Source Codes from the Book. Part 6
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@Stanislav Korotky Please can you help look into this error, I believe it started after MT5 updates because I knew the code works in the previous months without any modifications.
parameter convertion type 'long[][2]' to 'string[][] &' is not allowed SymbolFilter.mqh 199 20
I suspect the code below will help to replicate the issue:
void printSymbols() { SymbolFilter f; // filter object string symbols[]; // array for names long permissions[][2]; // array for data (property values) // list of requested symbol properties ENUM_SYMBOL_INFO_INTEGER modes[] = { SYMBOL_TRADE_MODE, SYMBOL_ORDER_MODE }; // apply the filter, get arrays with results f.let(SYMBOL_VISIBLE, true).select(true, modes, symbols, permissions); const int n = ArraySize(symbols); PrintFormat("===== Trade permissions for the symbols (%d) ===== ", n); for(int i = 0; i < n; ++i) { Print(symbols[i] + ":"); for(int j = 0; j < ArraySize(modes); ++j) { // display bit and number descriptions "as is" PrintFormat(" %s (%d)", SymbolMonitor::stringify(permissions[i][j], modes[j]), permissions[i][j]); } } }
parameter convertion type 'long[][2]' to 'string[][] &' is not allowed SymbolFilter.mqh 199 20
I suspect the code below will help to replicate the issue:
Please find the lines:
// we need this overload because built-in ArraySort // does not support arrays of strings void ArraySort(string &s[][]) const { QuickSortTm<string> qt(s); }
in the header files SymbolFilter.mqh and TradeFilter.mqh, and add the following method overload next to them:
// we need this overload because built-in ArraySort // does not support arrays of strings void ArraySort(string &s[][]) const { QuickSortTm<string> qt(s); } template<typename T> void ArraySort(T &s[][]) const { ::ArraySort(s); }PS. This question seems unrelated to the article.
Please find the lines:
in the header files SymbolFilter.mqh and TradeFilter.mqh, and add the following method overload next to them:
PS. This question seems unrelated to the article.Thank you for your quick response, after making the update, I got more errors saying:
parameter convertion type 'double[][2]' to 'string[][] &' is not allowed TradeFilter.mqh 338 20 cannot convert parameter 'double[][2]' to 'OrderMonitor&[][]' TradeFilter.mqh 338 20 parameter convertion type 'double[][2]' to 'string[][] &' is not allowed TradeFilter.mqh 338 20 cannot convert parameter 'double[][2]' to 'PositionMonitor&[][]' TradeFilter.mqh 338 20 parameter convertion type 'long[][2]' to 'string[][] &' is not allowed TradeFilter.mqh 163 17 cannot convert parameter 'long[][2]' to 'OrderMonitor&[][]' TradeFilter.mqh 163 17 parameter convertion type 'long[][2]' to 'string[][] &' is not allowed TradeFilter.mqh 163 17 cannot convert parameter 'long[][2]' to 'PositionMonitor&[][]' TradeFilter.mqh 163 17 etc..
I noticed that calling the generic QuickSortTm directly instead of the the ArraySort temporarily fixes the issue though I do not believe it is the optimal solution
QuickSortTm<V> qt(array);
//ArraySort(array);
That's strange, after the suggested fix above I have compiled and run this script /MQL5/Scripts/MQL5Book/p6/SymbolFilterTradeMode.mq5 successfully on build 5346. You did not show your source code.
I am running on Version 5 build 5327
void printActiveOrders() { OrderFilter filter; ENUM_ORDER_PROPERTY_DOUBLE properties[] = {ORDER_VOLUME_INITIAL, ORDER_PRICE_OPEN, ORDER_SL, ORDER_TP}; double d[][4]; ENUM_ORDER_TYPE types[]; ulong tickets[], magics[]; string symbols[], comments[]; filter.select(properties, tickets, d); filter.select(ORDER_SYMBOL, tickets, symbols); filter.select(ORDER_COMMENT, tickets, comments); filter.select(ORDER_TYPE, tickets, types); filter.select(ORDER_MAGIC, tickets, magics); Print("Orders .................. ", ArraySize(tickets)); for (int i=0; i < ArraySize(tickets); i++) { Print(tickets[i], "\t", magics[i], "\t", symbols[i], "\t", EnumToString(types[i]), " \t", NormalizeDouble(d[i][0],3), "\t", d[i][1], " \t ", d[i][2], " \t", d[i][3], "\t", comments[i]); } } void printPositions() { PositionFilter filter; ENUM_POSITION_PROPERTY_DOUBLE properties[] = {POSITION_PRICE_OPEN, POSITION_VOLUME, POSITION_SL, POSITION_TP, POSITION_PROFIT, POSITION_SWAP}; ENUM_POSITION_TYPE types[]; double d[][6]; ulong tickets[], extIds[]; string symbols[], comments[]; filter.let(POSITION_MAGIC, sets.MagicNumber).select(properties, tickets, d); filter.select(POSITION_SYMBOL, tickets, symbols); filter.select(POSITION_COMMENT, tickets, comments); filter.select(POSITION_TYPE, tickets, types); filter.select(POSITION_IDENTIFIER, tickets, extIds); Print("Tickets\t Parent Id\tSymbols \t Trade Type \t\t\t\t\t\tEntry \t Lots \t\t SL \t\t\t TP \t\t\t\t Profit \tSwat \t\tComments"); for ( int i =0; i < ArraySize(tickets); i++) { Print(tickets[i], "\t", extIds[i] == 0 ? "\t\t\t\t\t\t\t\t\t" : (string)extIds[i], "\t", symbols[i], "\t", EnumToString(types[i]), " \t", (string)NormalizeDouble(d[i][0],3), "\t", d[i][1], " \t ", d[i][2], " \t", d[i][3], " \t", d[i][4], " \t ", d[i][5], "\t", comments[i]); //Print(tickets[i], "\t", extIds[i] == 0 ? "\t\t\t\t\t\t\t\t\t" : extIds[i], "\t", symbols[i], "\t", EnumToString(types[i]), " \t", NormalizeDouble(d[i][0],3), "\t", d[i][1], " \t ", d[i][2], " \t", d[i][3], " \t", d[i][4], " \t ", d[i][5]); } }
On the side, I often see these messages:
This single line message always shows whenever I attach my EA to a chart: Unresolved int value as enum: 8 for MonitorInterface<ENUM_POSITION_PROPERTY_INTEGER,ENUM_POSITION_PROPERTY_DOUBLE,ENUM_POSITION_PROPERTY_STRING>::TradeState While these ones below shows when it is detached 2025.10.17 19:30:01.347 Deriv Trader (Volatility 10 (1s) Index.0,M15) 8 leaked strings left 2025.10.17 19:30:01.347 Deriv Trader (Volatility 10 (1s) Index.0,M15) 2 undeleted dynamic objects found: 2025.10.17 19:30:01.347 Deriv Trader (Volatility 10 (1s) Index.0,M15) 1 object of class 'WebSocketConnectionHybi' 2025.10.17 19:30:01.347 Deriv Trader (Volatility 10 (1s) Index.0,M15) 1 object of class 'MqlWebSocketTransport' 2025.10.17 19:30:01.347 Deriv Trader (Volatility 10 (1s) Index.0,M15) 576 bytes of leaked memory found
Forgive me for omitting my source, so I reverted to your suggested fix so I can get the errors again and it looks like these parts of my code are the parts that lead to the error according to the log
On the side, I often see these messages:
I overlooked that the letter T was already used as the class template typename (it's strange that the compiler did not produce an error in this case), so changing T to any other free letter will be ok, for example X:
template<typename X> void ArraySort(X &s[][]) const { ::ArraySort(s); }
As for the first warning, here is an explanation from the forums (which I gave to you earlier):
Forum on trading, automated trading systems and testing trading strategies
Experts: MQL5 Programming for Traders – Source Codes from the Book. Part 7
Stanislav Korotky, 2025.06.14 16:26
This is just a warning caused by the fact that the corresponding built-in enumeration of MQL5 has a gap in the constants which are normally assigned consecutively. This gap is occured because MQL5 is constantly changing, and some constants can become obsolete and then be eliminated. You can edit the source code to prevent such warnings.
And about the leaked memory - I'm afraid there is an omission in your custom source code, the book did not show such things. You should provide a complete test code to reproduce the problem.
PS. It's more efficient to run a single select for all properties of your interest:
// EXAMPLE: request profit, symbol, ticket for positions // by specific magic-number, sorted by profit #include <MQL5Book/Tuples.mqh> #include <MQL5Book/PositionFilter.mqh> #property script_show_inputs input ulong Magic; void OnStart() { int props[] = {POSITION_PROFIT, POSITION_SYMBOL, POSITION_TICKET}; Tuple3<double,string,ulong> tuples[]; PositionFilter filter; filter.let(POSITION_MAGIC, Magic).select(props, tuples, true); ArrayPrint(tuples); }
NB: I think moderators should move all questions and answers about the book (starting from #41) to appropriate thread, for example, here - https://www.mql5.com/en/forum/459067.
- 2023.12.15
- www.mql5.com
I overlooked that the letter T was already used as the class template typename (it's strange that the compiler did not produce an error in this case), so changing T to any other free letter will be ok, for example X:
As for the first warning, here is an explanation from the forums (which I gave to you earlier):
And about the leaked memory - I'm afraid there is an omission in your custom source code, the book did not show such things. You should provide a complete test code to reproduce the problem.
PS. It's more efficient to run a single select for all properties of your interest:
NB: I think moderators should move all questions and answers about the book (starting from #41) to appropriate thread, for example, here - https://www.mql5.com/en/forum/459067.
I believe you are right about the leak, I think I already have an idea where it is coming from.
Thank you so much brother.
void printActiveOrders() { int properties[] = {ORDER_VOLUME_INITIAL, ORDER_PRICE_OPEN, ORDER_SL, ORDER_TP, ORDER_TICKET, ORDER_MAGIC, ORDER_TYPE, ORDER_SYMBOL, ORDER_COMMENT}; Tuple9<double,double,double,double,long,long,long,string,string> values[]; OrderFilter filter; filter.select(properties, values); Print("\nFound: ", ArraySize(values), " Orders\n{ORDER_VOLUME_INITIAL, ORDER_PRICE_OPEN, ORDER_SL, ORDER_TP, ORDER_TICKET, ORDER_MAGIC, ORDER_TYPE, ORDER_SYMBOL, ORDER_COMMENT}"); ArrayPrint(values); } void printDeals() { DealFilter filter; int properties[] = {DEAL_TIME, DEAL_SYMBOL, DEAL_TICKET, DEAL_TYPE, DEAL_VOLUME, DEAL_PRICE, DEAL_COMMISSION, DEAL_PROFIT}; Tuple8<long,string,long,long,double,double,double,double> data[]; filter.select(properties, data, true); // Filter by time Print("\nFound: ", ArraySize(data), " Deals\nTIME, SYMBOL, TICKET, TYPE, VOLUME, PRICE, COMMISSION, PROFIT"); ArrayPrint(data); }
@Stanislav Korotky
I am can access the Deals and Orders and with this code but I have not been able to figure out how to access same for a specific timeframe. Please can you guide me on any doc or sample on how to do same for a specified timeframe
I am can access the Deals and Orders and with this code but I have not been able to figure out how to access same for a specific timeframe. Please can you guide me on any doc or sample on how to do same for a specified timeframe
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MQL5 Programming for Traders – Source Codes from the Book. Part 6:
In Part 6 of the "MQL5 Programming for Traders", we will study a key component of the MQL5 language – trading automation. We will start with a description of the fundamental entities, such as financial instrument specifications and trading account settings. These are prerequisites for creating properly operating Expert Advisors.
Author: MetaQuotes