Struct Initialisation Syntax Help

mlbarnes 2021.02.28 14:02

Maybe a quick question, but I'm struggling to find the answer myself.

I'm trying to initialise all elements of an array within a struct at struct definition, currently using a constructor.

I can't get the right syntax though, or maybe I can't do it this way? - Can someone help?

struct myStruct
  {double            priceData[];
   bool              signal;
   double            magnitude;
                     myStruct() { priceData[]={-1}; }   //--- Constructor
  };

Thanks - I think I found a pretty good solution myself in the end, but it may be longwinded so any additional thoughts would be great!

New code...

struct myStruct
  {
   double            priceData[];
   bool              signal;
   double            magnitude;
      //--- Constructor
   myStruct() {
   ArrayResize(priceData,1440,1440);
   ArraySetAsSeries(priceData,true);
   for(int i=0; i<1440; i++){priceData[i]=-1;};
   }
  };

Probably no need to SetAsSeries at this point?

lippmaje 2021.03.01 03:38 #1

   for(int i=0; i<1440; i++){priceData[i]=-1;};

There's also ZeroMemory and ArrayFill.

mlbarnes 2021.03.01 12:09 #2

lippmaje:

There's also ZeroMemory and ArrayFill.

Of course, I'm not thinking right...
I shall give that a test - my actual structures are more complicated still, but fingers crossed ZeroMemory will probably do what I want and I can ArrayFill the rest maybe!

Sorry for being dull - I've used these functions before, it just hadn't occured to me to use them in a constructor...
I'm just getting my head around OOP, but I guess the constructor is just code that runs whenever one of these structs is created and can contain any of these functions and more...

Thanks for the help.

My approach. The core Any rookie question, so Questions from Beginners MQL5

mlbarnes 2021.03.01 13:18 #3

mlbarnes:

Thanks for the help.

ZeroMemory does a pretty nice job, but it seems to reset some of my enumerated data fields to zero, others oddly to -1... can't tell why yet, but I'm experimenting...
<Experiments demonstrated that I am an idiot - it does reset them all to zero (which if you define them correctly has the correct enumeration!), which is exactly what I need.

I should add that my actual struct constructions are far more complicated than the example I gave above!

I'm still wondering if I might like some more specific way to both initialise and reset a complex structure...

I think I shall write a function to reset everything as I would want it - just like the constructor in the first place.
Which begs the question - is there some way to re-run the constructor code on a struct even after it has been initialised and used etc?
Does a struct definiton somehow work like a class? Can I make the constructor public? How then to call it and point it at the correct already constructed struct?

Maybe easier to just copy paste the 'reset code' into a new function, but I'm trying to learn stuff!

Array of class object Constructor of a structure OOP - calling the

lippmaje 2021.03.01 15:26 #4

You could build a 'Reset' function and call that from outside and from your constructor.

mlbarnes 2021.03.01 20:57 #5

lippmaje:
You could build a 'Reset' function and call that from outside and from your constructor.

Sounds simple enough, thanks for helping me think it through.
One question - if I call it from the constructor, which could be creating any number of different new variables, how do I reference the 'target variable'?

Need to call external Any rookie question, so Call function with a

lippmaje 2021.03.01 23:15 #6

'Target variable', what's that. Take a basic OO programming lession before going on.

The Reset function will be part of the struct scope and so has access to all members, of course.

Programming logic help Errors, bugs, questions Is a Public Struct

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