What does ptr() do?

[Smorg]

This is supposed to return pointers? Why does it only accept expressions and not functions with free variables? How do you dereference these "expressions"? Could someone maybe show some example usage?

[xPloit]

http://www.autoitscript.com/autoit3/docs/functions/Ptr.htm

[Smorg]

http://www.autoitscript.com/autoit3/docs/functions/Ptr.htm

Yes that would be what I read. This contains neither examples nor explanations. How is this useful? It just returns a pointer but provides no way of using it? Just there for your information or something? My guess is no because it has it's own datatype.

$x = ptr(1)
msgbox(0, '', VarGetType($x))

Alright clearly autoit remembers this is a ptr, not a string or number.

$x = ptr(1)
msgbox(0, '', addOne($x))


Func addOne($x)
    return $x + 1
EndFunc

ptr + int = ptr? That must be wrong.

Edited September 24, 2010 by Smorg

[xPloit]

This is supposed to return pointers? Why does it only accept expressions and not functions with free variables? How do you dereference these "expressions"? Could someone maybe show some example usage?

Reading the help file answers all of your questions

Returns the pointer representation of the expression.

Converts an expression into a pointer variant.

And I'm afraid I do not understand what you mean by dereference...

As for adding numbers to your string, that is impossible. "Hello" + "1" = ...? You can add strings together "Hello " + "there" = "Hello there" and you can add numbers together "1" + "2" = "3" But you cannot mix the two.

[AndyG]

  as mentioned before...

Returns the pointer representation of the expression.

$number=2345            ;some number could be a pointer
ConsoleWrite("Q: Is "&$number&" a Pointer?   A: "& (isptr($number)=1) & @crlf)

$no_pointer1="0x"&hex($number,4)         ;looks like a pointer
ConsoleWrite("Q: Is "&$no_pointer1&" a Pointer?   A: "& (isptr($no_pointer1)=1) & @crlf)

$no_pointer2="0x"&hex($number)            ;looks more like a pointer
ConsoleWrite("Q: Is "&$no_pointer2&" a Pointer?   A: "& (isptr($no_pointer2)=1) & @crlf)

$pointer=ptr($number)        ;a way to get a pointer
ConsoleWrite("Q: Is "&$pointer&" a Pointer?   A: "& (isptr($pointer)=1) & @crlf&@crlf)


$struct=DllStructCreate("dword[5]")
$pointer=DllStructGetPtr($struct)       ;an other way to get a pointer
ConsoleWrite("Q: DllStructGetPtr returns a pointer?    A: "& (isptr($pointer)=1)& @crlf)

for $i=1 to 5   ;every index of the struct
    $adress_dword=$pointer + 4 * $i    ;adress of each dword
    ConsoleWrite("Is the calculated adress "&$adress_dword&" of the dword a pointer?   A: "&(isptr($adress_dword)=1)&@crlf)
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