reference an Array object to dereference old one.

[Gholamhossein Eslamizadeh]

Hi, I have an array object named  "a" , after Appling a function to it, array object named "b" will be produced, for speed up proposes  I want to assign b pointer to a and free up  memory used by "a".

can any body help please.

void OnStart()
  { 
   A a[];
   A b[];
   ArrayResize(a, 2);
   ArrayResize(b,3);
   
   a[0].intA = 0;
   a[1].intA = 1;
   
   b[0].intA =2;
   b[1].intA = 3;
   b[2].intA = 4;
   
    a = b;
   
   Print(a[1].intA);
   // log should output 3 and a array size should be 3 and old a should be dereferenced to free up memory and b should be dereferenced to avid resource leak.
  } 
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
class A
  {
public:
   int               intA;
                     A()
     {
      intA = 1;
     }
  };

log should output 3 and a array size should be 3 and old a should be dereferenced to free up memory and b should be dereferenced to avid resource leak.

to stress it I will say again I do not want to use ArrayCopy , this function will copy data, I want to reference b to a.

[William Roeder]

Gholamhossein Eslamizadeh:  I want to assign b pointer to a and free up  memory used by "a".

to stress it I will say again I do not want to use ArrayCopy , this function will copy data, I want to reference b to a.

There are no pointers in MTx; only handles to classes, nothing to POD (arrays). What you want can not be done.

Either ArrayCopy and ArrayFree b, or free a and just use b

[Gholamhossein Eslamizadeh]

William Roeder:

There are no pointers in MTx; only handles to classes, nothing to POD (arrays). What you want can not be done.

Either ArrayCopy and ArrayFree b, or free a and just use b

Thanks for your response there is a function named GetPointer which get class pointers! I couldn't understand what reference said, but I think there may be a way to crack it.

this is as fur as i could go: 

//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
  {
//---
   A a[];
   A *ptr;
   ArrayResize(a, 2);
   a[0].intA = 0;
   a[1].intA = 1;
   ptr = CalculateFunction(a);
   Print(ptr.intA);
// log should output 3 and a array sie should be 3 and old a should be derefrenced to free up memory and b should be defrefrenced to avid resource leak.
  }

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
class A
  {
public:
   int               intA;
                     A()
     {
      intA = 1;
     }
  };

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
A * CalculateFunction(A &localA[])
  {
   A b;
   b[0].intA = 2;
   b[1].intA = 3;
   b[2].intA = 4;
   A * c[] = GetPointer(b);
   return c;
  }

https://www.mql5.com/en/docs/common/getpointer

[Dominik Egert]

You could overload the assignment operator in your class to capsule the functionality.

But you also need a class to capsule your array.

[William Roeder]

   A b;
   ⋮
   A * c[] = GetPointer(b);
   return c;

The moment you return, b goes out of scope and your pointer is invalid.

[Gholamhossein Eslamizadeh]

Dominik Egert:

You could overload the assignment operator in your class to capsule the functionality.

But you also need a class to capsule your array.

There is no benefit to that, I want to do so, in order to boost calculation speed, your approach will raise complexity and reduce speed way more than using ArrayCopy.

[Dominik Egert]

I don't think so. But I'll leave it up to you to find out.

Btw, overloading an Operator or calling a function is in fact the same.

I guess, it's a question of viewpoint. Maybe my imagination of the code is different than yours.

My idea would include a templated class and two overloaded assignment operators to capsule your requested feature.

I am not sure if the calling of these functions are significant to the speed of execution, compared to a procedural approach.

In fact I doubt it.

Edit: three overloaded operators.