TRUE in Masm

[jag]

I am trying to make a dll.
I follow the tutorial here: http://win32assembly.online.fr/tut17.html

I get this error: error A2006: undefined symbol : TRUE

Is the tutorial outdated and the constant TRUE has been removed from MASM? or is there something I did wrong?

Thanks.

[hutch--]

These two values have been defined in the WINDOWS.INC file since it was first created. They are specified in the SDK from Microsoft under win32.

Code Select Expand


TRUE                                 equ 1
FALSE                                equ 0


[jag]

Aye, dumb me.
I forgot to include windows.inc

Thank you Hutch. Originally I thought TRUE and FALSE were just built into MASM but now that I think about it that wouldn't make sense since in some cases FALSE could be 0 and in others, -1 but in Windows it's always one convention.

[gabor]

Hello!

Just a footnote: traditionally 0 is FALSE and any other value, so 1 too, is TRUE. That's why checking against 0 is also okay for logical testing. Comparing with 0 can be replaced when using registers by the OR operation. Like

Code Select Expand

    cmp al,TRUE   ; this sets Z if al was TRUE (match)
    jz @F
    ; al was false
    ...
@@:
    ; al was true
This does the same:

Code Select Expand

    or al,al   ; this set Z if al was 0 (0 or 0 = 0)
    jnz @F
    ; al was false
    ...
@@:
    ; al was true

Greets, Gábor

[Rockoon]

The 'safest' way to generate these values in most languages is with the idea that:

false = 0

and thus

true = (false == 0)

...it no longer matters what the underlying datatype is, or even that true is loosely or strictly defined.

There are many conventions for 'true' because they all happen to be usefull in one form or another. The '-1' crowd likes true to be part of masking operations, while the '1' crowd likes true to be more fluently used as an index or single bit.