Pointer to a variable

[Yashied]

Please advise how to get a pointer (address) to a variable ($a)?

local $a = 16

Edited March 16, 2009 by Yashied

[jvanegmond]

Not in AutoIt.

[PsaltyDS]

Not in AutoIt.

Unless you do it with a DLL struct:

; Create the struct and get it's pointer
Global $iA = 16
Global $tagA = "int A"
Global $tA = DllStructCreate($tagA)
Global $ptA = DllStructGetPtr($tA)

; Set the data
DllStructSetData($tA, "A", $iA)

; Use the pointer to extract the data
MsgBox(64, "DLL Success Test", "A = " & _GetData($ptA) & @CRLF & "@error = " & @error)

; Force an error
$ptA = 0
MsgBox(16, "DLL Error Test", "A = " & _GetData($ptA) & @CRLF & "@error = " & @error)

Func _GetData($ptPointer)
    Local $tRET = DllStructCreate($tagA, $ptPointer)
    Local $iRET = DllStructGetData($tRET, 1)
    Return SetError(@error, 0, $iRET)
EndFunc  ;==>_GetData

In this example, you can't get the pointer to $iA directly, but you can copy $iA into a struct and get the pointer of that.

[trancexx]

Unless you do it with a DLL struct:

; Create the struct and get it's pointer
Global $iA = 16
Global $tagA = "int A"
Global $tA = DllStructCreate($tagA)
Global $ptA = DllStructGetPtr($tA)

; Set the data
DllStructSetData($tA, "A", $iA)

; Use the pointer to extract the data
MsgBox(64, "DLL Success Test", "A = " & _GetData($ptA) & @CRLF & "@error = " & @error)

; Force an error
$ptA = 0
MsgBox(16, "DLL Error Test", "A = " & _GetData($ptA) & @CRLF & "@error = " & @error)

Func _GetData($ptPointer)
    Local $tRET = DllStructCreate($tagA, $ptPointer)
    Local $iRET = DllStructGetData($tRET, 1)
    Return SetError(@error, 0, $iRET)
EndFunc;==>_GetData

In this example, you can't get the pointer to $iA directly, but you can copy $iA into a struct and get the pointer of that.

Your structure is global. No need for _GetData() function:

MsgBox(64, "DLL Success Test", "A = " & DllStructGetData($tA, 1))

Same thing as for pointer thoug I can see what could be your point(er).

Yashied likely meant something else.

Edited March 16, 2009 by trancexx

[Yashied]

Your structure is global. No need for _GetData() function:

MsgBox(64, "DLL Success Test", "A = " & DllStructGetData($tA, 1))

Same thing as for pointer thoug I can see what could be your point(er).

Yashied likely meant something else.

trancexx, you are right. I want to access a variable (not structure) knowing only the address and type. But I think that this is not possible in AutoIt (different syntax). Although the structure is the same, but less convenient than a direct appeal to the variable.

[PsaltyDS]

trancexx, you are right. I want to access a variable (not structure) knowing only the address and type. But I think that this is not possible in AutoIt (different syntax). Although the structure is the same, but less convenient than a direct appeal to the variable.

All AutoIt variables are a C-type variant, and the properties of the variant for the different AutoIt variable types is not meant to be exposed to the scripter. Valik doesn't even like that the VarGetType() function exists.

So even if you got a pointer to the $a variable, it would be to a variant that required more processing to see that it was a variant containing an INT32 and where the actual value was. At least that's my understanding from a non-C programmer peek behind the curtain. Smarter people can and often do correct me.