| Description |
The Pointer type provides a general use pointer to any memory based variable. That is, one that is accessed by reference.
Objects, AnsiStrings, and arrays are examples of reference based variables.
But be warned : untyped pointers are dangerous - it is normally always better to use a specific pointer reference to the data type you are using. Only then can you act up on the pointer, as in the example.
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| Example code : Referring to the current form using a Pointer variable |
// Full Unit code.
// -----------------------------------------------------------
// You must store this code in a unit called Unit1 with a form
// called Form1 that has an OnCreate event called FormCreate.
unit Unit1;
interface
uses
// The System unit does not need to be defined
Forms, Dialogs;
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm} // Include form definitions
procedure TForm1.FormCreate(Sender: TObject);
var
generalPtr : Pointer; // A pointer to anything
formPtr : ^TForm; // A pointer to a form object
begin
// The current unit's form is addressable via the self keyword
generalPtr := Addr(self);
// We can assign this pointer to the form pointer
formPtr := generalPtr;
// And set the form caption to show this
formPtr.Caption := 'Test program';
end;
end.
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| Hide full unit code |
The form is shown with caption:
Test program
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