• Mark Evans <mevans zyvex.com> Jun 25 2001
• Jan Knepper <jan smartsoft.cc> Jun 25 2001
• Mark Evans <mevans zyvex.com> Jun 25 2001
• "Walter" <walter digitalmars.com> Jun 25 2001
• "Kar Gay Lim" <kagay kimay.net> Jun 26 2001

Mark Evans <mevans zyvex.com> writes:

Is the byte size of an HWND under Win16 large model officially 2 bytes or 4?

I would suppose that like any other far pointer, it would be 4 bytes.  However
as a test, I did the following in a WINIO program:

	printf("sizeof(HWND) = %ld",(long) sizeof(HWND));

and got

	sizeof(HWND) = 2

This is a little surprising.  Is the sizeof() function automatically assuming a
near pointer when in fact an HWND can be near or far?  What is the story here?

Maybe the sizeof HWND was always 2 bytes under Win16 but I was never a Win16
guru.

Mark

Jan Knepper <jan smartsoft.cc> writes:

I don't think HWND was a pointer on Win16, but a handle and the number of
handles is limited.

HTH

Jan


Mark Evans wrote:

 Is the byte size of an HWND under Win16 large model officially 2 bytes or 4?

 I would suppose that like any other far pointer, it would be 4 bytes.  However
as a test, I did the following in a WINIO program:

         printf("sizeof(HWND) = %ld",(long) sizeof(HWND));

 and got

         sizeof(HWND) = 2

 This is a little surprising.  Is the sizeof() function automatically assuming
a near pointer when in fact an HWND can be near or far?  What is the story here?

 Maybe the sizeof HWND was always 2 bytes under Win16 but I was never a Win16
guru.

 Mark

Mark Evans <mevans zyvex.com> writes:

Well I know it's a handle, but that's just a pointer to a pointer to data.  The
amount of indirection is not the issue.  The size in bytes of the data type is
the issue.

Are you saying that a Win16 HWND is in fact two bytes, which in turn limits the
number of HWNDs?  Are HWNDs stored in some "magic segment" such that the
segment information is 
not needed at runtime?

I looked at the typedef in Windows.h, and it's nontrivial, but in the end looks
like 2 bytes to me....please confirm.  I don't need too much information about
the whys and wherefores of 
Win16, just confirmation that my head is screwed on straight thinking that HWND
is two bytes.  It came as a surprise.

Thanks,

Mark


On Mon, 25 Jun 2001 14:28:58 -0400, Jan Knepper <jan smartsoft.cc> wrote:
 I don't think HWND was a pointer on Win16, but a handle and the number of
handles is limited.
 
 HTH
 
 Jan
 
 
 Mark Evans wrote:
 
 Is the byte size of an HWND under Win16 large model officially 2 bytes or 4?

 I would suppose that like any other far pointer, it would be 4 bytes.  However
as a test, I did the following in a WINIO program:

         printf("sizeof(HWND) = %ld",(long) sizeof(HWND));

 and got

         sizeof(HWND) = 2

 This is a little surprising.  Is the sizeof() function automatically assuming
a near pointer when in fact an HWND can be near or far?  What is the story here?

 Maybe the sizeof HWND was always 2 bytes under Win16 but I was never a Win16
guru.

 Mark

"Walter" <walter digitalmars.com> writes:

It's always 16 bits in win16. -Walter

Mark Evans wrote in message <1104_993494621 evans>...
Well I know it's a handle, but that's just a pointer to a pointer to data.


type is the issue.
Are you saying that a Win16 HWND is in fact two bytes, which in turn limits


segment information is
not needed at runtime?

I looked at the typedef in Windows.h, and it's nontrivial, but in the end


information about the whys and wherefores of
Win16, just confirmation that my head is screwed on straight thinking that


Thanks,

Mark


On Mon, 25 Jun 2001 14:28:58 -0400, Jan Knepper <jan smartsoft.cc> wrote:
 I don't think HWND was a pointer on Win16, but a handle and the number of




 HTH

 Jan


 Mark Evans wrote:

 Is the byte size of an HWND under Win16 large model officially 2 bytes






 I would suppose that like any other far pointer, it would be 4 bytes.






         printf("sizeof(HWND) = %ld",(long) sizeof(HWND));

 and got

         sizeof(HWND) = 2

 This is a little surprising.  Is the sizeof() function automatically






the story here?
 Maybe the sizeof HWND was always 2 bytes under Win16 but I was never a






 Mark

"Kar Gay Lim" <kagay kimay.net> writes:

You have to understand that Win16 is "medium" memory model.

i.e. Data segment in the DLL is only 64k and hence the limited
system resources.  The handles are 16-bit for that reason.

Walter <walter digitalmars.com> wrote in message
news:9h8t4s$1b07$1 digitaldaemon.com...
 It's always 16 bits in win16. -Walter

 Mark Evans wrote in message <1104_993494621 evans>...
Well I know it's a handle, but that's just a pointer to a pointer to data.


 type is the issue.
Are you saying that a Win16 HWND is in fact two bytes, which in turn limits


 segment information is
not needed at runtime?

I looked at the typedef in Windows.h, and it's nontrivial, but in the end


 information about the whys and wherefores of
Win16, just confirmation that my head is screwed on straight thinking that


Thanks,

Mark


On Mon, 25 Jun 2001 14:28:58 -0400, Jan Knepper <jan smartsoft.cc> wrote:
 I don't think HWND was a pointer on Win16, but a handle and the number of




 HTH

 Jan


 Mark Evans wrote:

 Is the byte size of an HWND under Win16 large model officially 2 bytes






 I would suppose that like any other far pointer, it would be 4 bytes.






         printf("sizeof(HWND) = %ld",(long) sizeof(HWND));

 and got

         sizeof(HWND) = 2

 This is a little surprising.  Is the sizeof() function automatically






 the story here?
 Maybe the sizeof HWND was always 2 bytes under Win16 but I was never a






 Mark