C / C++ / MFC

23-Dec-05 0:36

what's the use of unsigned char? if char is going to be characters?? -a , +a ??
and also tell me who to display it in an AfxMessageBox Frown | :(

regards,
Rookie
Installing MFC...2% complete

Russell^'23-Dec-05 0:52

Russell^'

23-Dec-05 0:52

You can use unsigned char (for example) to read single byte from file without re-interpreter it as integer (positive or negative values).
But, In typical programs, the use is quite the same.

To use the AfxMessageBox you can use it in the same way of the char.
But your question is strange:
the string is build with caratchars and they are translated in a defined numerical range: so if you want to display strange values (like 190) you will obtain only strange sign!!

Merry Christmas
Have a nice code day Wink | ;)

toxcct23-Dec-05 2:18

23-Dec-05 2:18

char is quite bad named because its name confuses too much the newbies.
of course, char goes to be used in strings, but first, that's not always true, and secondly, it does not serves only for that.

char in C/C++ is simply a signed byte, not more, not less. that means it can be used as a character (in strings), but also as an integer of 8 bits, or as a simple 8 bits array.

about the signature, yes, a char is by default signed, which means it contains values between [-128 ; +127].

but usually, the mainly used characters in the ascii tables are under the code 127 (over that, they are called extended char sets).
if you want more than that, you'll have to use UNICODE instead of ASCII, which stores a character on 16 bits instead...

to display a char string, simply use the "" notation, ,and the compiler will format your variable as needed ('\0' terminated)...

TOXCCT >>> GEII power
[toxcct][VisualCalc 2.20][VisualCalc 3.0]

Nemanja Trifunovic24-Dec-05 10:09

Nemanja Trifunovic

24-Dec-05 10:09

toxcct wrote:
char in C/C++ is simply a signed byte, not more, not less

It is simply a byte, but it can be signed or unsigned - it is left to compiler implementations to decide. For instance with VC++, char is signed by default unless the option /J is specified.

My programming blahblahblah blog. If you ever find anything useful here, please let me know to remove it.

-- modified at 16:10 Saturday 24th December, 2005

To Delete Objects created by IMPLEMENT_DYNACREATE

segment_fault3-Jan-06 18:02

segment_fault

3-Jan-06 18:02

I'd suggesting creating a typdef as follows:

typedef unsigned char to BYTE;

BYTE's are pretty useful in walking through raw data streams, manipulating graphics by having to twiddle the bits of various pixels, etc.

Read more of what I have to say at http://directx9.blogspot.com/

birajendu22-Dec-05 23:38

birajendu

22-Dec-05 23:38

hi....
I would like to Destroy MainFrame object Created by IMPLEMENT_DYNACREATE macro.coz, it gives memory leak when i close my apllecatin window.

plz...help he...how i colud do for this...

birajendu
CyberG India
Delhi
India

Re: To Delete Objects created by IMPLEMENT_DYNACREATE

Sheng Jiang 蒋晟24-Dec-05 9:28

Sheng Jiang 蒋晟

24-Dec-05 9:28

It deletes itself automatically after the window is destroyed. Check if you stopped your message pump prematurely.

My blogs:

http://blog.joycode.com/jiangsheng
http://blog.csdn.net/jiangsheng
http://bloglines.com/public/jiangsheng

Command what is yours
Conquer what is not
---Kane

RGBQUAD in Bitmap Class

vikas amin22-Dec-05 23:29

vikas amin

22-Dec-05 23:29

I am creating a class for Bitmap.

I want to have detials regarding the RGBQUAD
which specifies the colors used in the bmp file

Cool | :cool:

Vikas Amin
Embin Technology
Bombay
vikas.amin@embin.com

Re: RGBQUAD in Bitmap Class

toxcct22-Dec-05 23:46

Re: RGBQUAD in Bitmap Class

22-Dec-05 23:46

why reinventing the wheel ??

BITMAP structures already exist.

moreover, what is supposed to be the "quad" part of the name ?
RGB stands for red-green-blue ; quad is for...?

TOXCCT >>> GEII power
[toxcct][VisualCalc 2.20][VisualCalc 3.0]

Russell^'22-Dec-05 23:56

Russell^'

22-Dec-05 23:56

Hope this helps.
http://www.priyank.in/docs/bmp.php[^]

Merry Christmas
Have a nice code day Wink | ;)

Re: RGBQUAD in Bitmap Class

Amal P23-Dec-05 0:23

Amal P

23-Dec-05 0:23

Hi,

Usually we creates the bitmap info directly from BITMAPINFO structure. But you can derive another structure from it. Then you will have access to RGBQUAD values. For knowing how to derive a structure from BITMAPINFO see the below code.

struct DIBINFO : public BITMAPINFO
{
RGBQUAD arColors[255]; // Adds an extra 255 entries to palette

operator LPBITMAPINFO() { return (LPBITMAPINFO) this; }
operator LPBITMAPINFOHEADER() { return &bmiHeader; }
RGBQUAD* ColorTable() { return bmiColors; }
};

Now instead of creating a Bitmap Info object of BITMAPINFO structure create it using DIBINFO structure. It is just simple as,

DIBINFO m_bitmapInfo;

Now you can change the RGBQUAD palette by changing the values in the arColors of the bitmap. For example here i am changing the palette to a gray scale one by filling same values at Blue, Green and Red.

for(int i = 0; i < 255; i++)
{
m_bitmapInfo.arColors[i].rgbBlue = i;
m_bitmapInfo.arColors[i].rgbGreen = i;
m_bitmapInfo.arColors[i].rgbRed = i;
m_bitmapInfo.arColors[i].rgbReserved = i;
}

There is another reserved member. It may be used in some other cases as Alpha. Normaly when you tell the color of a pixel you will specify 4 values.

They are,
1. Value of Red.
2. Value of Green.
3. Value of Blue.
4. Value of Alpha.
The alpha can be considered as the transparency.

Now while creating a bitmap pass the bitmap info as m_bitmapInfo. It will do the trick.

Thanks and Regards,
Amal P.

#if

Smith#22-Dec-05 22:54

22-Dec-05 22:54

"As another example if running program on MSDOS machine we want to include file msdos.h otherwise a default.h file. A macro SYSTEM is set (by OS) to type of system so check for this: "

#if SYSTEM == MSDOS
#include <msdos.h>
#else
#include ``default.h''
#endif

--------------------
but how the value of "MSDOS" is obtained??

regards,
Rookie
Installing MFC...2% complete

Owner drawn22-Dec-05 23:10

Owner drawn

22-Dec-05 23:10

Rokiee wrote:
but how the value of "MSDOS" is obtained??

Try this

printf("MSDOS = %d", MSDOS);

Hope this is what you meant... Sniff | :^)

Happy christmas friends. May the Love of My Lord and Saviour Jesus bring forth Joy and Happiness into your life too.
<marquee direction="up" height="50" scrolldelay="1" step="1" scrollamount="1" hspace="2" vspace="2">
--Owner Drawn
--Nothing special
--Defeat is temporary but surrender is permanent
--Never say quits
--Jesus is Lord

Smith#22-Dec-05 23:37

22-Dec-05 23:37

sorry, i asked it wrong. i want to know like,
eg:
if(x==3)
{
//
}
else
{

}

here if only we know the value of 'x' we can check it right?? so i mean how do u get the value for "SYSTEM".? is it set somewhere out of the program??

regards,
Rookie
Installing MFC...2% complete

toxcct22-Dec-05 23:18

22-Dec-05 23:18

Rokiee wrote:
but how the value of "MSDOS" is obtained??

you mean, how to set SYSTEM macro with MSDOS value ?
like this :

#define SYSTEM MSDOS

otherwise, if you want to actually test for the real Operating System to know if the program is running under DOS or not, you won't be able to do this at preprocessing time.
it is only at run time you will get the OS version and to one or one action...

TOXCCT >>> GEII power
[toxcct][VisualCalc 2.20][VisualCalc 3.0]

Smith#22-Dec-05 23:40

22-Dec-05 23:40

please refer my replies. above and below

regards,
Rookie
Installing MFC...2% complete

Re: #if [edited]

toxcct22-Dec-05 23:41

22-Dec-05 23:41

nope, you're wrong.
please refer the original question

sorry, i thought i talked to somebody else Big Grin | :-D

TOXCCT >>> GEII power
[toxcct][VisualCalc 2.20][VisualCalc 3.0]

-- modified at 6:05 Friday 23rd December, 2005

Re: #if [edited]

Eytukan23-Dec-05 0:37

Eytukan

23-Dec-05 0:37

"But your mind is very complex, very tricky. It makes simple things complicated. -- that's its work. And for centuries it has been trained for only one thing: to make things so complicated that your life becomes impossible."- Osho

<marquee scrollamount="1" scrolldelay="1" direction="up" height="10" step="1">
--[V]--

khan++22-Dec-05 23:35

khan++

22-Dec-05 23:35

I think you want to automatically include files according to the compiler.
Here is the macro for Turbo C++ which I think is provided by the compiler:
__MSDOS__

So you would write:

#ifdef __MSDOS__<br />
#include "msdos.h" //whatever<br />
#else<br />
#include "other.h"<br />
#endif

http://www.sm.u-bordeaux2.fr/~corsini/Pedagogie/SCM/scm/Automatic_C_Preprocessor_Definitions.html[^]

this is this.

Smith#22-Dec-05 23:39

22-Dec-05 23:39

at compile time , _MSDOS_ would be true("defined") ,if its run in DOS right??

regards,
Rookie
Installing MFC...2% complete

toxcct22-Dec-05 23:43

22-Dec-05 23:43

Rokiee wrote:
_MSDOS_ would be true("defined") ,if its run in DOS right??

definitely not ! Frown | :(

refer my other answers

TOXCCT >>> GEII power
[toxcct][VisualCalc 2.20][VisualCalc 3.0]

Smith#22-Dec-05 23:50

22-Dec-05 23:50

so is it a way to talk to the compiler? the

like , #ifdef _MSDOS_ (if the system runs on DOS)
include....

??

regards,
Rookie
Installing MFC...2% complete

toxcct22-Dec-05 23:58