Article: Effective usage of Arrays in MQL

Quoting HarriFF

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Thanks for the working example using vectors @Nicholishen. Generally I find the collection classes in MT4 a bit lacking. Sets, for example. Im your stuff will come in useful

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Quoting HarriFF

Disliked

Thanks for the working example using vectors @Nicholishen. Generally I find the collection classes in MT4 a bit lacking. Sets, for example. Im your stuff will come in useful

Ignored

#property strict
#include <Arrays\ArrayInt.mqh>
 
class SetInt : public CArrayInt
{
   public: bool Add(const int element)
   {
      if(SearchLinear(element) < 0)
         return CArrayInt::Add(element);
      return false;
   }
};
 
void OnStart()
{
   SetInt int_set;
   MathSrand(GetTickCount());
  
   for(int i=0;i<1000;i++)
   {
      int num = 1+(rand()%10);
      if(int_set.Add(num))
         Print("Added ",num);
   }
}

Quoting HarriFF

Disliked

Hello The library that you referenced seems to be in a state of flux: last update from 5 days ago, and I got compilation errors when I tried to compile - see screenshot. However, the code snippet you provided does work, albeit, just for ints. Its based on CArrayInt from Metaquotes and CArray doesnt have the useful functions SearchLinear, Add, etc., so Im going to try to genericise it. {image}

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Quoting Nicholishen

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{quote} I'll hook you up next week... I'm the mean time can you post your config for that sick dark theme?

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Quoting HarriFF

Disliked

{quote} Tools -> Option -> Color tab, main change is swap black letters on white background to white letters on black background. Some of the other colours may not show up so clearly, but I just adjust them. Ive defined a GenericArray, based on ArrayInt, which uses templates to accept any datatype. And then Ive defined Set.mqh as a subclass of GenericArray. Both compile ok, but when I try to use I get compilation errors "template mismatch"? All the files are attached. {file} {file} {file}

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Quoting HarriFF

Disliked

Hello The library that you referenced seems to be in a state of flux: last update from 5 days ago, and I got compilation errors when I tried to compile - see screenshot. However, the code snippet you provided does work, albeit, just for ints. Its based on CArrayInt from Metaquotes and CArray doesnt have the useful functions SearchLinear, Add, etc., so Im going to try to genericise it. {image}

Ignored

#include <Lib\Collection\Set.mqh>
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
{
//---
   MathSrand(GetTickCount());
   
   Set<int> set;
   for(int i=0;i<1000;i++)
   {
      int num = 1+(rand()%10);
      if(set.add(num))
         Print("Adding ",num);
   }
}

Quoting Nicholishen

Disliked

{quote} You forgot to specify the template data-type. So instead of GenericArray arr; you have to use GenericArray<double> arr;

Ignored

bool GenericArray::Add(const T element) [b]const [/b]{

bool GenericArray::Add(const T element) {

//+------------------------------------------------------------------+
//|                                                    IntMatrix.mq4 |
//|                                                      nicholishen |
//|                                   www.reddit.com/u/nicholishenFX |
//+------------------------------------------------------------------+
#property copyright "nicholishen"
#property link      "www.reddit.com/u/nicholishenFX"
#property version   "1.00"
#property strict
#include <Arrays\ArrayInt.mqh>
#include <Arrays\ArrayObj.mqh>
class MyIntArray : public CArrayInt
{
   public: bool operator += (const int element) { return Add(element);}
};
//+------------------------------------------------------------------+
class DynamicMatrix : public CArrayObj
{
   public:MyIntArray* operator[](const int index)
   {
      if(index < Total())
         return (MyIntArray*)At(index);
      MyIntArray *temp = NULL;
      while(index >= Total())
      {
         temp = new MyIntArray();
         Add(temp);
      }
      return temp;
   }
};
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
{
//---
   int c = 1;
   srand(GetTickCount());
   DynamicMatrix m;
   int iMax = rand()%10+1;
   for(int i=0;i<iMax;i++)
   {
      int jMax = rand()%10+1;
      for(int j=0;j<jMax;j++)
         m[i]+= c++;
   }    
   for(int i=0;i<m.Total();i++)
      for(int j=0;j<m[i].Total();j++)
         Print("[",i,"][",j,"] = ",m[i][j]);
}
//+------------------------------------------------------------------+

void function6(int &arrays[50])
  {
   int vals = ArraySize(arrays);
   int trailingstop = TimeCurrent() - (arrays[function5(arrays) - 1]);
   while(trailingstop > Trigger)
     {
      arrays[function5(arrays) - 1] = 0;
      trailingstop = TimeCurrent() - (arrays[function5(arrays) - 1]);
      if(function5(arrays) < 2)
         break;
     }
  }
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
int function5(int &arrays[50])
  {
   int vals = ArraySize(arrays);
   for(int k = 0; k < vals; k++)
      if(!(arrays[k] > 0))
         return (k);
   return (vals - 1);
  }
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
void function4(double &val[50])
  {
   int vald = ArraySize(val);
   for(int l = vald; l > 0; l--)
      val[l] = val[l - 1];
   val[0] = 0;
  }
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
void function3(int &arrays[50])
  {
   int vald = ArraySize(arrays);
   for(int l = vald; l > 0; l--)
      arrays[l] = arrays[l - 1];
   arrays[0] = 0;
  }