How to sort struct variables in MT4?

[Brian Lillard]

Hi

I'm using a struct for collecting the data which includes spreads and their instances.

struct _buffer{int spread; int instances;};

_buffer WellingtonSpread[];

The thing needed is a sorting method for these two variables in the struct by either descending or ascending.

[Seng Joo Thio]

Brian Lillard:

I'm using a struct for collecting the data which includes spreads and their instances.

The thing needed is a sorting method for these two variables in the struct by either descending or ascending.

If I'm not wrong, you have only two options when it comes to sorting arrays...

(1) Use ArraySort (https://www.mql5.com/en/docs/array/arraysort), which is not useful if you want to select which of the fields in your struct to be sorted.

(2) Use CArray (https://www.mql5.com/en/docs/standardlibrary/datastructures/carray), but you'll have to define your own sort routine.

[William Roeder]

Seng Joo Thio: 

(1) Use ArraySort (https://www.mql5.com/en/docs/array/arraysort), which is not useful if you want to select which of the fields in your struct to be sorted.

(2) Use CArray (https://www.mql5.com/en/docs/standardlibrary/datastructures/carray), but you'll have to define your own sort routine.

1. ArraySort only processes n dimensional arrays by the first dimension. It can not process structs at all.

2. Here's my generic sort.
             Sort multiple arrays - MQL4 and MetaTrader 4 - MQL4 programming forum
             Array or not to array - Trading Positions - MQL4 and MetaTrader 4 - MQL4 programming forum - Page 2

3. CList can also sort.
             pass generic class data field - Swing Trades - MQL4 and MetaTrader 4 - MQL4 programming forum

[fxsaber]

Forum on trading, automated trading systems and testing trading strategies

How to sort struct variables in MT4?

Brian Lillard, 2019.05.01 05:03

I'm using a struct for collecting the data which includes spreads and their instances.

struct _buffer{int spread; int instances;};

_buffer WellingtonSpread[];

The thing needed is a sorting method for these two variables in the struct by either descending or ascending.

Форум по трейдингу, автоматическим торговым системам и тестированию торговых стратегий

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fxsaber, 2019.05.01 17:30

Удобная сортировка массива структур

#property strict

// Сортировка массива структур и указателей на объекты по (под-) полю/методу.
#define ArraySortStruct(ARRAY, FIELD)                                            \
{                                                                                \
  class SORT                                                                     \
  {                                                                              \
  private:                                                                       \
    template <typename T>                                                        \
    static void Swap( T &Array[], const int i, const int j )                     \
    {                                                                            \
      const T Temp = Array[i];                                                   \
                                                                                 \
      Array[i] = Array[j];                                                       \
      Array[j] = Temp;                                                           \
                                                                                 \
      return;                                                                    \
    }                                                                            \
                                                                                 \
    template <typename T>                                                        \
    static int Partition( T &Array[], const int Start, const int End )           \
    {                                                                            \
      int Marker = Start;                                                        \
                                                                                 \          
      for (int i = Start; i <= End; i++)                                         \
        if (Array[i].##FIELD <= Array[End].##FIELD)                              \
        {                                                                        \
          SORT::Swap(Array, i, Marker);                                          \
                                                                                 \
          Marker++;                                                              \
        }                                                                        \
                                                                                 \
       return(Marker - 1);                                                       \
    }                                                                            \
                                                                                 \
    template <typename T>                                                        \
    static void QuickSort( T &Array[], const int Start, const int End )          \
    {                                                                            \
      if (Start < End)                                                           \
      {                                                                          \
        const int Pivot = Partition(Array, Start, End);                          \
                                                                                 \
        SORT::QuickSort(Array, Start, Pivot - 1);                                \
        SORT::QuickSort(Array, Pivot + 1, End);                                  \
      }                                                                          \
                                                                                 \
      return;                                                                    \
    }                                                                            \
                                                                                 \
  public:                                                                        \
    template <typename T>                                                        \ 
    static void Sort( T &Array[], int Count = WHOLE_ARRAY, const int Start = 0 ) \
    {                                                                            \
      if (Count == WHOLE_ARRAY)                                                  \
        Count = ::ArraySize(Array);                                              \
                                                                                 \
      SORT::QuickSort(Array, Start, Start + Count - 1);                          \
                                                                                 \
      return;                                                                    \
    }                                                                            \
  };                                                                             \
                                                                                 \
  SORT::Sort(ARRAY);                                                             \
}

Use

struct _buffer{int spread; int instances;};

_buffer WellingtonSpread[];

void OnStart()
{
  ArraySortStruct(WellingtonSpread, spread);    // Sort by spread.
  ArraySortStruct(WellingtonSpread, instances); // Sort by instances.
}

[nwesterhuijs]

fxsaber #:

Use

Hi fxsaber,

I tried to see if I can modify for use in MT4, but no luck so far. Any clues on how to make it usable for MT4?

Thanks,

Norbert 

[Fernando Carreiro]

nwesterhuijs #: Hi fxsaber, I tried to see if I can modify for use in MT4, but no luck so far. Any clues on how to make it usable for MT4? Thanks, Norbert 

What do you mean? The above code is for MQL4 — there is nothing to modify!

[nwesterhuijs]

Fernando Carreiro #:

What do you mean? The above code is for MQL4 — there is nothing to modify!

Got a string of errors when just copy, paste and compile, so after some minor debugging efforts assumed it to be for mq5. After your comment tried it on a different machine and it compiled without issues. Will check tomorrow what happened and dive into the code a bit deeper to see what it does.

Thanks for your response, much appreciated.  

[wmirandamor]

fxsaber #:

Use

Thanks for your code, helps me a lot