Delphi pointer arithmetic

How should this line of code be writed to allow it to compile

MoveMemory(poleFileDescriptorW
         , (oleDataPointer + SizeOf(oleFileDescriptorW) *Index + 4)^
         , SizeOf(oleFileDescriptorW));

Particularly this part

(oleDataPointer + SizeOf(oleFileDescriptorW)*Index + 4)^

I am just want to shift the pointer by SizeOf(oleFil开发者_运维知识库eDescriptorW)*Index + 4 bytes

Variables are defined as:

pOLEFileDescriptorW : ^FILEDESCRIPTORW;
oleDataPointer : Pointer;

Cast to an integer type, do the math and cast back.

I usually used Cardinal but I think that doesn't work with a 64 bit compiler.

Pointer(NativeInt(oleDataPointer) + SizeOf(oleFileDescriptorW)*Index + 4)

If you're using DELPHI >= 2009, set $POINTERMATH to ON and you can use pointer arithmetic directly

MoveMemory and the identical CopyMemory functions accept pointers, not variables, as the Delphi RTL function Move requires (and this is the only difference between MoveMemory and Move).

So you shouldn't dereference the pointer. Just do

MoveMemory(poleFileDescriptorW,
           (oleDataPointer + SizeOf(oleFileDescriptorW)*Index + 4),
           SizeOf(oleFileDescriptorW));

where each argument is a pointer/cardinal. Depending on your actual data types, you might need to do some trivial casting. For instance, you might need to do PSomeType(cardinal(myPointer) + cardinal(myPointer2)).

Anyhow, if you would sometime need to dereference a pointer, you need to specify its type.

(oleDataPointer + SizeOf(oleFileDescriptorW)*Index + 4)^

couldn't possibly work (why?). Do

PMyType(cardinal(oleDataPointer) + SizeOf(oleFileDescriptorW)*Index + 4)^

Typecast to Integer.

 Pointer(Integer(oleDataPointer) + SizeOf(oleFileDescriptionW) * Index + 4)

And Andreas was right that you should use pointers directly. See if that works.

God bless