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Accessing memory explicitly

Posted on 1998-09-20
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Last Modified: 2010-04-06
[Note: I am using Delphi 2.0]

If XPtr and YPtr are pointer variables and Offset is an integer/word/longint/etc., is it legal to do the following?

XPtr := YPtr + Offset;

(in case you're curious, in my application XPtr is a pointer to a bitmap and I want to get the memory location Offset bytes from the beginning)

In Delphi 2, I noticed that the seg and ofs functions are obsolete.

I have not tried compiling the unit that uses the XPtr := YPtr + Offset yet, but I assume it is legal.  If it is, would someone confirm this, and if it is not, please tell me how to do it.  Thanks.




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Question by:scrapdog
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Madshi earned 0 total points
ID: 1340339
scrapdog,

it is legal. But be careful with the types!!!

var XPtr,YPtr : ^integer;
    Offset    : integer;

inc(XPtr,integer(YPtr)+Offset);  
// don't do it this way, because Delphi then thinks that you mean:
// inc(XPtr^,integer(YPtr)+Offset);

// do it this way...
XPtr:=pointer(integer(YPtr)+Offset);

Regards, Madshi.
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