array of pointers

[sk.Silvia]

hi there, i want to make an array of pointers as follows

Delphi-Quellcode:

type pointer_array=array[0..50] of pointer;
var Pointers:pointer_array;

      procedure HandleInput(Message1:string; var ExportVar:real);
          begin
          inc(Step_input);
          Pointers[Step_input]:=ExportVar; //DONT WORK
          Pointers[Step_input]:=^ExportVar; //DONT WORK
          ^Pointers[Step_input]:=^ExportVar; //DONT WORK
          //unimportant commands here
          end;

what i want to do, is to store a pointer to each variable imported to procedure
(HandleInput('0', CXC)-> ExportVar=CXC -> i will store a pointer to CXC)
how to do it?

thanks

[JasonDX]

You need the address of a variable, which you'll store in a Pointer. To get the Address of a Variable, use the @-Operator.
In your case it would be then:

Delphi-Quellcode:

Pointers[Step_input] := @ExportVar

greetz
Mike

[sk.Silvia]

great:))

and now when i will to get the value of the variable on what it shows

Delphi-Quellcode:

ExportVar:=10;
Pointers[Step_input] := @ExportVar;
how do i get the value 10 from Pointers[Step_input]

[sk.Silvia]

Delphi-Quellcode:

procedure HandleInput(Message1:string; var ExportVar:real);
var i1:integer;
    adr:real;
          begin
          Pointers[Step_input]:=@ExportVar;
          @adr:=Pointers[i1];
          
          ShowMessage(FloatToStr(adr));
          
          end;

i tried to make this, but it isnt working (@adr:=Pointers[i1]; - cannot assign left side)

[JasonDX]

You have to dereference the Pointer. This usually works like this:

Delphi-Quellcode:

IntegerValue := PointerToInteger^

But, since you're not using typed Pointers, you have to tell, that this is an integer, so a simle cast is enaugh:

Delphi-Quellcode:

IntegerValue := Integer(Pointers[Step_input]^)

btw, code is always easier to read, if you use typed Pointers (means: ^integer instead of Pointer), so if you intend to store only one Datatype in those Pointers, youse typed Pointers ;)

greetz
Mike

[sk.Silvia]

Dankeshon, its working fine, thanks:)

[sk.Silvia]

well but there is a problem

http://www.politea.sk/employ/elvenone/cccc.jpg

the adress of ExportVar and Ratio is the same, thats OK
but why is the value of tmpr not same as the value of Ratio=ExportVar (the value of tmpr is 0 and the value of Ratio is 1,58 )?

[JasonDX]

Zitat:

Zitat von sk.Silvia

the adress of ExportVar and Ratio is the same, thats OK
but why is the value of tmpr not same as the value of Ratio=ExportVar (the value of tmpr is 0 and the value of Ratio is 1,58 )?

On the left side of your Code you see a fiew blue points. In some lines these blue points are missing. This means, that this line of code has not been compiled, most times, because it was unnecessary. Here you're propably not using the variable temp anymore after the assignment, so it is unnecessary to execute that operation.
As short answer: the variable temp has the value 0, because the value has not been assigned for optimation reasons.
There are two ways to avoid this:

1. you do something with the variable after the assignment. A ShowMessage(FloatToStr(temp)), for example.
2. you disable compiler Optimation for the necessary lines of code, by using the {$O+/-}-Flags.

greetz
Mike