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Data Structures | Follow Up

Posted on 2004-08-01
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Last Modified: 2010-04-05
Q is follow up of http:Q_21077801.html

Detailing a bit of Dynamic Arrays and how to get the size of them plus some tips and tricks...
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Question by:Cerf
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Slick812 earned 1000 total points
ID: 11690698
I will guess that you need the sizeOf for some kind of memory copy of array data?
if you have used fixed arrays you can get the array Data by the array variable's pointer address

var
aryFixed: TPMem51;

begin
CopyMemoy(@aryFixed, pPointer, SizeOf(aryFixed));
 - - - - - - - - -

but this will NOT work with dynamic arrays because the variable is jus a pointer to a delphi reference that handles the dynamic array, to use a pointer location for a dynamic arrat, I use the address of the first element

var
 _tData: Array of Word;

begin
// setlength and whatever
 pData := @_tData[0]; // first element of array for memory address od the array data


however, a SizeOf( ) for ANY TObject, or dynamic array (a String type is a dynamic array) it will ALWAYS return 4 , because these Objects and dynamic arrays are Pointers, because objects and dyn arrays are ReAllocated memory blocks,
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