Features of the mql5 language, subtleties and tricks - page 223

[fxsaber]

Koldun Zloy #:

How about this?

I can't test it.

[Koldun Zloy]

fxsaber #:

Don't check.

QuickSort library here

[fxsaber]

Koldun Zloy #:

The QuickSort library is here

Thanks, that's a very good option! I seem to have QuickSort too, but for some reason it's wildly slow.

Your option could be wrapped in macros somehow to make it faster to use...

[Koldun Zloy]

fxsaber #:

Thanks, that's a very good option! I seem to have QuickSort as well, but for some reason the brakes are wild.

Your option could be wrapped in macros to make it faster to use....

I don't see why you need macros. It's very simple as it is.

[Maxim Kuznetsov]

how to properly format something that looks like this in C:

int sort(void *arr,size_t isize,size_t size, int (*cmp)(void *item1,void *item2)); /// типовой прототип sort с функцией сравнения

???

trying to sort through templates:

template <typename T>

int sort(T &arr[],int (*cmp)(const T &,const T&))
{

}

doesn't work - you can't put a function pointer into the argument. There must be a separate typedef

but typedef can't (or can it??) be a template.

macroms grow out of these problems :-)

[mktr8591]

Maxim Kuznetsov #:

how to properly format something that looks like this in C:

int sort(void *arr,size_t isize,size_t size, int (*cmp)(void *item1,void *item2)); /// типовой прототип sort с функцией сравнения

???

We're trying to use templates:

fails - you can't put a function pointer in the argument. There must be a separate typedef

but typedef cannot (or can it??) be a template....

macroms grow out of these problems :-)

template <typename T> struct SORT
  {
   typedef int       (*cmp)(const T &, const T&);
   static  int       Do(T &arr[], cmp) {return 0;}
  };

int SortInt(const int &, const int &) {return 0;}

void OnStart()
  {
   int arr[];
   SORT<int>::Do(arr, SortInt);
  }

[mktr8591]

I discovered an unobvious feature of MQL (and C++)

class C1
  {
public:
   virtual void      f1(int p = 1) {Print(p);}
  };
class C2: public C1
  {
public:
   virtual  void     f1(int p = 2) {Print(p);}
  };

void OnStart()
  {
   C2 obj;
   C1 *p = &obj;
   p.f1();        //Prints "1"
  }

That is, the default value is substituted into the parameter (p) at the point of method call (p.f1()) and this value is taken from the method description in class C1 - the declared type of variable ptr, not the real type of object obj.

(Which, in general, is logical).

[Andrey Dik]

Forum on trading, automated trading systems and testing trading strategies

Errors, bugs, questions

Andrey Dik, 2022.06.24 08:38

MQL_VISUAL_MODE is a special case of MQL_TESTER?

MQL_OPTIMIZATION is a special case of MQL_TESTER?

I mean, MQL_TESTER includes both MQL_VISUAL_MODE and MQL_OPTIMIZATION?

I need the EA to perform some actions when working on a chart and in visual mode, but not in all other cases. I can't figure out how to select the right flags for this case when checking MQLInfoInteger()?

I could do it very simply, for example, like this:

if (MQLInfoInteger(MQL_VISUAL_MODE) || MQLInfoInteger(MQL_CHART_MODE))

{

  //выполняем некоторые действия

}

but the MQL_CHART_MODE flag is not provided in mql5.

does anyone have any thoughts?

[Maxim Kuznetsov]

Andrey Dik #:

Anybody have any thoughts?

if (ChartID()!=0) {

    // Graphical chart presents
    // draws on it

}

[Andrey Dik]

Maxim Kuznetsov #:

if (ChartID()!=0) {

    // Graphical chart presents
    // draws on it

}

What does that mean? Can you expand on that?