Jump to content

  • Log In with Google      Sign In   
  • Create Account

Banner advertising on our site currently available from just $5!


1. Learn about the promo. 2. Sign up for GDNet+. 3. Set up your advert!


Win32 BOOL and bool ?


Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.

  • You cannot reply to this topic
10 replies to this topic

#1 Endemoniada   Members   -  Reputation: 361

Like
0Likes
Like

Posted 14 July 2014 - 03:34 PM

Hi guys,

 

In Win32 (Visual Studio) is bool exactly the same as BOOL ?

 

What exactly is BOOL ?

 

typedef int BOOL

or maybe

#define BOOL int

or something else ?

 

I'd rather use bool but want to make sure it's really the same.

 

Thank you.

 



Sponsor:

#2 fastcall22   Crossbones+   -  Reputation: 5772

Like
3Likes
Like

Posted 14 July 2014 - 03:36 PM

The Win32 API is a C library. C does not have a boolean type. Therefore, Win32 has defined BOOL as being an integer having zero and nonzero for false and true respectively.

EDIT:
See Win32 Data Types.

Edited by fastcall22, 14 July 2014 - 03:40 PM.

QWxsIHRvYXN0LXRvYXN0aW5nIHRvYXN0ZXJzIGNhbiB0b2FzdCB0b2FzdGVkIHRvYXN0LCBhbHRob3Vn aCByZS10b2FzdGluZyB0b2FzdGVkIHRvYXN0IGlzIGdlbmVyYWxseSBub3QgcmVjb21tZW5kZWQgYnkg dGhlIG1hbnVmYWN0dXJlcnMgb2YgdG9hc3QtdG9hc3RpbmcgdG9hc3RlcnMuLi4=

#3 Washu   Senior Moderators   -  Reputation: 6974

Like
9Likes
Like

Posted 14 July 2014 - 03:37 PM

bool is a C++ type, BOOL is a win32 typedef for int, but the underlying type should not matter (hence why its typedeffed).

 

If you're writing a C++ app, use bool, if you're interfacing with Win32, use BOOL.


In time the project grows, the ignorance of its devs it shows, with many a convoluted function, it plunges into deep compunction, the price of failure is high, Washu's mirth is nigh.
ScapeCode - Blog | SlimDX


#4 SiCrane   Moderators   -  Reputation: 10826

Like
8Likes
Like

Posted 14 July 2014 - 09:32 PM

Note that sometimes the use of BOOL in the Windows API is a lie and is not actually a boolean. For the GetMessage() function, 0 indicates WM_QUIT, non-zero indicates a non-WM_QUIT message except for -1 which means an error. 



#5 rnlf   Members   -  Reputation: 1369

Like
0Likes
Like

Posted 15 July 2014 - 02:26 AM

Note that sometimes the use of BOOL in the Windows API is a lie and is not actually a boolean. For the GetMessage() function, 0 indicates WM_QUIT, non-zero indicates a non-WM_QUIT message except for -1 which means an error. 

wacko.png WAT?

 

Are they crazy? (Rhetorical question).

 

I actually had to double-check that info on MSDN, I thought you were trolling. But you're not. And that frightens me to death.



#6 mhagain   Crossbones+   -  Reputation: 9865

Like
1Likes
Like

Posted 15 July 2014 - 06:20 AM

 

Note that sometimes the use of BOOL in the Windows API is a lie and is not actually a boolean. For the GetMessage() function, 0 indicates WM_QUIT, non-zero indicates a non-WM_QUIT message except for -1 which means an error. 

wacko.png WAT?

 

Are they crazy? (Rhetorical question).

 

I actually had to double-check that info on MSDN, I thought you were trolling. But you're not. And that frightens me to death.

 

 

There's probably a legacy reason for that - maybe something to do with the original GetMessage in an earlier version of Windows returning a strict BOOL, but when they moved it to 32-bit (or something else, I don't know) they needed to return another value but couldn't change the function signature for compatibility reasons.  Windows is full of stuff like that - check out Raymond Chen's blog for more info.


It appears that the gentleman thought C++ was extremely difficult and he was overjoyed that the machine was absorbing it; he understood that good C++ is difficult but the best C++ is well-nigh unintelligible.


#7 rnlf   Members   -  Reputation: 1369

Like
0Likes
Like

Posted 15 July 2014 - 06:47 AM

In that case, they have made a function with a completely different interface that actually breaks backward compatibility. They could as well have renamed the return type at the same time or made a second function.



#8 mhagain   Crossbones+   -  Reputation: 9865

Like
2Likes
Like

Posted 15 July 2014 - 07:13 AM

In that case, they have made a function with a completely different interface that actually breaks backward compatibility. They could as well have renamed the return type at the same time or made a second function.

 

Ahh, here we go: http://blogs.msdn.com/b/oldnewthing/archive/2013/03/22/10404367.aspx

 

We can infer from that (and the "somebody said" linked post) that the addition of -1 as a return code happened during the changeover from Windows 3.0 and 3.1 when parameter validation was added to these functions.  As for the alternatives you suggest in your second sentence, I obviously don't know the reason why they didn't, but I'm going to assume that there was such a reason.


Edited by mhagain, 15 July 2014 - 07:25 AM.

It appears that the gentleman thought C++ was extremely difficult and he was overjoyed that the machine was absorbing it; he understood that good C++ is difficult but the best C++ is well-nigh unintelligible.


#9 SiCrane   Moderators   -  Reputation: 10826

Like
1Likes
Like

Posted 15 July 2014 - 08:33 PM

I actually had to double-check that info on MSDN, I thought you were trolling. But you're not. And that frightens me to death.

When it comes to the Windows API, you don't need to make stuff up. For that matter I couldn't make some of this stuff up if I tried. Another true but unbelievable detail about BOOL: there's not just one typedef or two typedefs for boolean types in the API, but three of them (that I know about): BOOL, BOOLEAN and VARIANT_BOOL. They are respectively, 4 bytes, 1 byte and 2 bytes. VARIANT_BOOL is especially interesting because it doesn't use non-zero for true but specifically 0xffff (-1 as a short). Also BOOL and VARIANT_BOOL are signed, and BOOLEAN is unsigned. BOOLEAN is a fun one because you can do accidental integer conversions that don't mean what you think they do. bool(my_int) means true if my_int is non-zero. BOOLEAN(my_int) means take the least significant byte (in other words 256 would look like false).

#10 mhagain   Crossbones+   -  Reputation: 9865

Like
2Likes
Like

Posted 16 July 2014 - 06:12 AM

BOOL vs. VARIANT_BOOL vs. BOOLEAN vs. bool

 

Again, there's a reason for everything.  I'm not necessarily saying that all of them are good reasons, just that they are reasons.

 

i guess that this is a characteristic of an API that's developed over 30-odd years.  We see the same in legacy OpenGL where there are often 5 different ways of doing the same thing, and not consistently specified.


It appears that the gentleman thought C++ was extremely difficult and he was overjoyed that the machine was absorbing it; he understood that good C++ is difficult but the best C++ is well-nigh unintelligible.


#11 Endurion   Crossbones+   -  Reputation: 4191

Like
3Likes
Like

Posted 16 July 2014 - 08:04 AM

The consensus for the Windows defined types is, usually you DO NOT mix them. Pass a BOOL to a BOOL etc. Don't assume, just because they sound samey, that they are the same. There's usually a reason why they added a new type instead of reusing an existing one.
Fruny: Ftagn! Ia! Ia! std::time_put_byname! Mglui naflftagn std::codecvt eY'ha-nthlei!,char,mbstate_t>




Old topic!
Guest, the last post of this topic is over 60 days old and at this point you may not reply in this topic. If you wish to continue this conversation start a new topic.



PARTNERS