How to use struct elements via index?

2020-06-23T06:41:36.475000Z

If you have cracked your problem, would you mind posting/sharing it here?
Thanks

How to use struct elements via index?

2020-06-23T05:08:38.642000Z

It looks like every DataExchangeN in your code means different DataExchange.
I have only 1 DataExchange and hundreds of variables with different datatype in this DataExchange.

So what I want is likely

Collection[0] point to DataRead.Data1,
Collection[1] point to DataRead.Data2,
..
Collection[N] point to DataRead.DataN+1.

I will try if pointer can do this, thanks.

How to use struct elements via index?

2020-06-22T09:16:43.432000Z

Sorry for my bad statement and thanks for your answer. => okay I guess?

You are (from what I understand) trying to describe an array of pointers to your elements instances but i have difficulties in understandiong your writing, so I could misinterpret it.

( pointers are dangerous when not initialised correct )
Collection : ARRAY [0..31] OF POINTER TO DataExchange;
(* I am not sure on this ^ statement! it could also be a pointer to DWORD as adresses are mostly DWORDS)

( Always initialise the array of pointers in the beginning of your code and continously before you use them. This might be tedious but then again it helps you from crashes and whatnot! )

( INIT Pseudo code, must be run at start of every cycle(!) in order to survive
"online change" )
Collection[0] := ADR(DataExchange00)
Collection[1] := ADR(DataExchange01)
Collection[2] := ADR(DataExchange03)
..
..
Collection[N] := ADR(DataExchangeN)
Collection[N+1] := ADR(DataExchangeN+1)

( Writing Usage Example Pseudo )
Collection[2]^.Data1 := .. ;
Collection[2]^.Data2 := .. ;
Collection[2]^.Data3 := .. ;

( reading Usage Pseudo)
.. := Collection[1]^.Data1;
.. := Collection[1]^.Data2;
.. := Collection[1]^.Data3;

Good luck!

How to use struct elements via index?

2020-06-22T08:34:10.943000Z

Hi aliazzz.

Actually I have hundreds of elements with different datatype in the struct DataExchange, which means there are Data1 .. Data1000(or more).
The names of element are illustrative, actually they are irregular.
I have only 1 DataExchange named DataRead, and I want to use index as parameter to call the element I need.
For example, when I want to call Data50, I may use index 50 to call this element, instead of using DataRead.Data50.
But I have no idea how to implement it.

Sorry for my bad statement and thanks for your answer.

How to use struct elements via index?

2020-06-22T06:16:50.418000Z

Try this out;

Declaration

Exchange : ARRAY [0..31] OF DataExchange;

Usage

Exchange[0].Data1 := a;
Exchange[0].Data2 := b;
Exchange[0].Data3 := c;
..
..
Exchange[31].Data1 := x;
Exchange[31].Data2 := y;
Exchange[31].Data3 := z;

Offcourse 0..31 and a,b,c,x,y,z are illustrative.

Regards,

Aliazzz

How to use struct elements via index?

2020-06-22T03:19:06.984000Z

Hi, I have a struct with elements in different datatype, for example:

TYPE DataExchange :
STRUCT
Data1 : INT;
Data2 : WORD;
Data3 : DWORD;
END_STRUCT
END_TYPE

VAR
DataRead : DataExchange;
END_VAR

Is there any way to use the elements in the struct via index?
It means using
DataRead[0] := 0 instead of DataRead.Data1 := 0,
DataRead[1] := 0 instead of DateRead.Data2 := 0, etc.

Thanks.

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