An array of a struct - example

struct TSupRes{
   int value;
   double indizes[];
   double type[];
   int noOfHighs;
   int noOfLows;
   int noOfLowHighs;
   };

   TSupRes supRes[];
   // Resizing the whole array
   ArrayResize(supRes,10,10);
  // Resizing the indizes array of the first(0) element
   ArrayResize(supRes[0].indizes,5,5);
  
   // Looping through my arr and some settings and output for testing!
   for (int k=0; k<ArraySize(supRes);k++){  
      ArrayResize(supRes[k].indizes,5);
      supRes[k].noOfLows=2+k;
      supRes[k].indizes[0]=3;
      Alert(k+":"+supRes[k].noOfLows);
      Alert(k+":"+supRes[k].indizes[0]);
   }

//+------------------------------------------------------------------+
//|                                 SimpleCollectionClassExample.mq4 |
//|                                      Copyright 2017, nicholishen |
//|                         https://www.forexfactory.com/nicholishen |
//+------------------------------------------------------------------+
#property copyright "Copyright 2017, nicholishen"
#property link      "https://www.forexfactory.com/nicholishen"
#property version   "1.00"
#property strict
#include <Arrays\List.mqh>
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
class SimpleRates : public CObject
{
protected:
   string         m_symbol;
   MqlRates       m_rates[];
   int            m_total_rates;
public:
   SimpleRates(string symbol):m_symbol(symbol)
   { 
      ArraySetAsSeries(m_rates,true);
      Refresh(); 
   }
   
   void Refresh()
   {
      m_total_rates = CopyRates(m_symbol,Period(),0,Bars(m_symbol,Period()),m_rates);
   }   
   double Close(int index){ return m_rates[index].close;}
   string Symbol(){ return m_symbol;}
   int TotalRates(){ return m_total_rates; }
};
void OnStart()
{
//---
   CList list;
   for(int i=0;i<5;i++)
      list.Add(new SimpleRates(SymbolName(i,false)));
  
  //print each symbol's last 3 close prices
   for(SimpleRates *symbol=list.GetFirstNode();symbol!=NULL;symbol=symbol.Next())
      for(int i=0;i<3 && i < symbol.TotalRates();i++)
         Print(symbol.Symbol(),"[",i,"] close = ",symbol.Close(i));
}
//+------------------------------------------------------------------+

Quoting Nicholishen

Disliked

Just a friendly FYI, It's better to use CObject derived classes and the MQL collection classes instead of classic C-style arrays. With the former you get dynamic allocation and automatic memory management, and the latter is a PITA. Here is a quick example I whipped to to demonstrate how easy it is to implement //+------------------------------------------------------------------+ //| SimpleCollectionClassExample.mq4 | //| Copyright 2017, nicholishen | //| https://www.forexfactory.com/nicholishen | //+------------------------------------------------------------------+...

Ignored

Quoting reteid2222

Disliked

{quote} thx...didn t thought this as so easy...!

Ignored

template < typename T > class Array {
T data[];
}
 
Array< MqlRates > rates;
Array< int > ints;

Quoting braintheboss

Disliked

Better use templates... template < typename T > class Array { T data[]; } Array< MqlRates > rates; Array< int > ints;

Ignored

template<typename T>
class objvector : public CArrayObj
{
public:
   T operator[](const int index) const { return At(index); }
};

objvector<MyClass*> my_vector;

bool compare( double n1, double n2, bool direction ) {
 
return( (n1 > n2 )== direction);
};
double low1=1;
double low2=3;
double high1=3;
double high2=1;
 
compare( low1,low2,0 ); //true if "low1" is lower "low2"
compare( high1,high2,1 );//true if "high1" is higher "high2"

Quoting Nicholishen

Disliked

{quote} This still limits you considerably. No automatic dynamic allocation, no sorting, no searching, no inserting, no comparing, etc. The std lib collection classes take all this hard work off your hands, and if you want something like C++ vector it's as simple as template<typename T> class objvector : public CArrayObj { public: T operator[](const int index) const { return At(index); } }; and then to use it... objvector<MyClass*> my_vector;

Ignored

Quoting braintheboss

Disliked

{quote} I only placed a simple skeleton. Std lib Array class is very limited, at least under my point of view and needs...

Ignored

Quoting Nicholishen

Disliked

{quote} So you would rather code you own from scratch instead of deriving a subclass? Damn son...I'm too lazy for all that

Ignored

Quoting braintheboss

Disliked

{quote} I'm more lazy if I have duplicate code and files. Every coder have their way...

Ignored

#property strict
#include <Arrays\List.mqh>
////
class SymbolRsi : public CObject
{
protected:
   string         m_symbol;
public:
   SymbolRsi(string symbol):m_symbol(symbol){}
   string Symbol() {return  m_symbol;}
   double Rsi()const
   {
      return iRSI(m_symbol,Period(),14,PRICE_CLOSE,0);
   }
   int Compare(const CObject *node,const int mode=0)const override
   {
      SymbolRsi *other = (SymbolRsi*)node;
      if(this.Rsi()>other.Rsi()) return -1;
      if(this.Rsi()<other.Rsi()) return 1;
      return 0;
   }
};
/////
class RsiCollection : public CList
{
public:
   void RsiCollection()
   {
      for(int i=0;i<SymbolsTotal(false);i++)
         Add(new SymbolRsi(SymbolName(i,false)));
      CList::Sort(0);
   }
   void Refresh()
   {
      CList::Sort(0);
   }
};
/////
void OnStart()
{
   RsiCollection rsi_list;
   Print("top 3");
   SymbolRsi *s=rsi_list.GetFirstNode();
   for(int i=0;i<3 && s!=NULL;s=s.Next(),i++)
      Print(s.Symbol(),": RSI = ",s.Rsi());
   Print("bottom 3");
   s=rsi_list.GetLastNode();
   for(int i=0;i<3&&s!=NULL;s=s.Prev(),i++)
      Print(s.Symbol(),": RSI = ",s.Rsi());
}
//+------------------------------------------------------------------+

Quoting Nicholishen

Disliked

{quote} I respect that. I'm always open to new methods and I'm curious how you implement collections... For example, let's say you want to sort your symbols in the market watch by RSI. How would you do it without using collection classes? Here is an example that took me about 5 minute to fully implement using the std library. How could I do this better, more efficient? #property strict #include <Arrays\List.mqh> //// class SymbolRsi : public CObject { protected: string m_symbol; public: SymbolRsi(string symbol):m_symbol(symbol){} string Symbol()...

Ignored

Quoting braintheboss

Disliked

{quote} I have my full library ported from C++ ( linux ). Then i have similar stuff that MQL library but in my way. Cleaner, faster and versatile... I use for lists different approaches. For example capture shows graphic object settings class with iterator for all types ( I use bit map list ) {image}

Ignored

Quoting Nicholishen

Disliked

{quote} Interesting... but it still doesn't answer the question... How could I do this better, more efficient?

Ignored

Quoting braintheboss

Disliked

{quote} It dont exists one way. It depends you need. For that I have different approaches and I use the best for that task...

Ignored

Quoting Nicholishen

Disliked

{quote} Ok so in the example I gave, a pretty common MQL challenge, how would you do it?

Ignored

Quoting braintheboss

Disliked

{quote} Its fine that approach for a sequential list of objects. Normally its the convenient way when you want create a chain of filters like looks the example. I have in my Trend tool a chain of filters with 2 nodes in every one creating a pre and post process in every MA in the chain. In this way I can create infinite MAs combinations without have code anything. But as i told you before depends you need in every moment

Ignored

Quoting Nicholishen

Disliked

{quote} Ok, but that seems to be a pretty unique case and a specialized collection. I think for the purposes of getting back on topic we were discussing how to generally manage collections of objects no matter what the object is or how it's used. You stated it's better to use templates, but didn't provide a link to your library. How is OP supposed to implement your collection classes without your library?

Ignored