C / C++ / MFC

Re: Seeking in Large Files

3-Jun-05 2:39

I've not ever used FAT32, but it supports a maximum file size of 2³²-1 bytes. That would prohibit your 5GB file from working on Windows 98.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

RichardS3-Jun-05 3:36

RichardS

3-Jun-05 3:36

Hi David,

You are quite right. That's why the C-runtime calls were working well as you could seek 2GB - 2 distance. But now with XP/2000/NT we have the problems.

regards,
Rich

"Programming today is a race between software engineers striving to build bigger and
better idiot-proff programs, and the Universe trying to produce bigger and better idiots.
So far the Universe is winning." -- Rich Cook

Re: Seeking in Large Files

Blake Miller3-Jun-05 4:20

Blake Miller

3-Jun-05 4:20

And for whatever it is worth, if you install the C runtime library source code and trace through it far enough, you will find it just ends up mapping all the standard C file flags and functions into calls into the Win32 API anyways.
I had to use that as defense to the argument when someone tried to tell me the C runtime was faster than the Win32 API - how could it be, after a slew of mapping operations, the C runtime functions ended up calling the Win32 API functions anyways...

StreamOut doesn't preserve CFM_LINK settings

P. Gnana Prakash2-Jun-05 22:19

P. Gnana Prakash

2-Jun-05 22:19

Hi Everybody,

In my rich edit application, I just discovered CFM_LINK and am enjoying having clickable links in my CRichEditCtrl. However, when I use streamOut and streamIn to save my control contents to disk and back, all the RTF formatting is preserved except for the links. Please guide me how to save the RTF document along with the hyperlink.

Regards,
Prakash.

A Journey of thousand miles must begin with a single step.

Windows Media Player, GetVolume(), always return -600?

Koms Bomb2-Jun-05 22:09

Koms Bomb

2-Jun-05 22:09

XP, no SP, the WMP is the one binds with XP.
I put a WMP control on a MFC dialog, then I play it, and adjust the volume.
I want to save the volume when exits, so I tried GetVolume, but it always
returns -600 (the default volume value).
Why? What have I missed? Did any one experience this?

I've post this in MS newsgroup, but got no answers.

Thanks.

Re: Windows Media Player, GetVolume(), always return -600?

P-Rex2-Jun-05 22:20

P-Rex

2-Jun-05 22:20

Can you provide some code?

P.

Re: Windows Media Player, GetVolume(), always return -600?

Koms Bomb2-Jun-05 22:26

Koms Bomb

2-Jun-05 22:26

Sorry, the code is in my home and I'm in office now.
My steps are,
1, Right click on th dialog then select Insert ActiveX control,
2, Select Windows Media Player and put it on the dialog,
3, Run the app and play something,
4, When a button click, I call the Medial Player's GetVolume to get the volume, but the result is always -600 even I've change the volume bar.

big endian to little endian

GDavy2-Jun-05 22:09

GDavy

2-Jun-05 22:09

I am receiving a binary buffer in big endian on a little endian machine.
Is there an SDK func that can convert big buffers from big endian to little endian???

Thx for any help,
Greetings,
Davy

Re: big endian to little endian

RichardS2-Jun-05 23:08

RichardS

2-Jun-05 23:08

Hi Davy,

I don't know of a SDK to do it, but switching endian's isn't a big deal. You can do the following:

<br />
typedef struct _tagByteBreak<br />
{<br />
   unsigned char bUpperByte;<br />
   unsigned char bMiddleByte1;<br />
   unsigned char bMiddleByte2;<br />
   unsigned char bLowerByte;<br />
} BYTE_BREAK;<br />
<br />
typedef union _tagEndianSwitch<br />
{<br />
   BYTE_BREAK stBreak;<br />
   unsigned long int ulFull;<br />
} ENDIAN_SWITCH;<br />
<br />
void UTIL_SwitchEndian (unsigned long int *pulIn)<br />
{<br />
   ENDIAN_SWITCH Endian;<br />
   unsigned char btemp;<br />
<br />
   Endian.ulFull = *pulIn;<br />
<br />
   btemp = Endian.stBreak.bLowerByte;<br />
   Endian.stBreak.bLowerByte = Endian.stBreak.bUpperByte;<br />
   Endian.stBreak.bUpperByte = btemp;<br />
   btemp = Endian.stBreak.bMiddleByte1;<br />
   Endian.stBreak.bMiddleByte1 = Endian.stBreak.bMiddleByte2;<br />
   Endian.stBreak.bMiddleByte2 = btemp;<br />
<br />
   *pulIn = Endian.ulFull;<br />
}<br />

This code takes a unsigned long int (32-bits) at swops the endian (either direction). Now all you need is a loop:

<br />
void ConvertEndian (unsigned long int szLen, unsigned long int *pulBuf)<br />
{<br />
   for (unsigned long int i = 0; i < szLen; ++i)<br />
   {<br />
      UTIL_SwitchEndian (&pulBuf[i]);<br />
   }<br />
}<br />

This will convert the buffer to the opposite endian system. It should be easy to modify for 16-bits.

regards,
Rich

"Programming today is a race between software engineers striving to build bigger and
better idiot-proff programs, and the Universe trying to produce bigger and better idiots.
So far the Universe is winning." -- Rich Cook

Re: big endian to little endian

GDavy2-Jun-05 23:39

GDavy

2-Jun-05 23:39

Thanks for the thorough answer!
Rose | [Rose]

Greetings,
Davy

Re: big endian to little endian

cmk5-Jun-05 12:37

cmk

5-Jun-05 12:37

You have to know the layout of the buffer.
If it is just an array of numbers than you do something like what Richard suggests.

More often though the buffer is the contents of a struct or class.
In that case you have to swap the members.

e.g.
struct ST {
long l;
short s;
float f;
double d;
};

You get a buffer:
char *buff = ...;

Cast buffer to structure:
struct ST *st = (struct ST*)buff;

Swap members:
st->l = SWAP4(st->l);
st->s = SWAP2(st->s);
st->f = SWAP4(st->f);
st->d = SWAP8(st->d);

where SWAP*() swaps the specified number of bytes.
e.g.
#define SWAP2(x) ( ((x) << 8) | ((x) >> 8) )

#define SWAP4(x) ( ((x) << 24) | ((x) >> 24) | \
( ((x) & 0x0000ff00) << 8 ) | \
( ((x) & 0x00ff0000) >> 8 ) \
)

#define SWAP8(x) ( ((x) << 56) | ((x) >> 56) | \
( ((x) & 0x000000000000ff00) << 40 ) | \
( ((x) & 0x0000000000ff0000) << 24 ) | \
( ((x) & 0x00000000ff000000) << 8 ) | \
( ((x) & 0x000000ff00000000) >> 8 ) | \
( ((x) & 0x0000ff0000000000) >> 24 ) | \
( ((x) & 0x00ff000000000000) >> 40 ) \
)

...cmk

Save the whales - collect the whole set

How to use EnumSystemLanguageGroups

Hachaso2-Jun-05 21:27

2-Jun-05 21:27

Hi!

I'm having trouble using this API callback function, EnumSystemLanguageGroups.
When I compile I get this error message:

c:\Documents and Settings\bsosla\Desktop\Regional Settings Plugin\Regional Settings\Regional Settings\regionalSettingsPlugin.cpp(457): error C3861: 'EnumSystemLanguageGroups': identifier not found, even with argument-dependent lookup

Reading a little about this callback function I see that I have to include winnls.h and windows.h, adding the library kernel32.lib.
All this is done but without any results.

What am I doing wrong?

Thanks!

David Crow3-Jun-05 2:49

3-Jun-05 2:49

Hachaso wrote:
...error C3861: 'EnumSystemLanguageGroups': identifier not found, even with argument-dependent lookup

This is not a Visual Studio v6 error. Are you using Visual Studio v7.x instead?

Have you seen this?

Hachaso wrote:
Reading a little about this callback function I see that I have to include winnls.h and windows.h...

Actually, only winnls.h is required. You get that one by default if you are already including windows.h.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Hachaso6-Jun-05 21:00

6-Jun-05 21:00

Hi!

Thanks for helping me!

I'm using Visual Studio .NET 2003. I guess that its version 7.

Do you think that the problem can be related to what kind of project I've started?

When I create a Win32 project, letting the Wizard create the base code, then add my lines I get no compile error. But adding the same lines to another existing project returns an error. This is why I'm wondering if it has to do with what kind of project I start?

Thanks!

David Crow7-Jun-05 3:01

7-Jun-05 3:01

At this point, I would compare the project settings of the one that works with the one that doesn't work.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Hachaso7-Jun-05 21:34

7-Jun-05 21:34

Hi Again!

Thank you once more for helping me out.

I've compared and can't find any difference that would solve the problem.

I've looked at the weblink you gave me. That's the page that I've been looking at all
the time. My problem is that they explain what the function does and what the different
parameters do but they don't give you any example code.
For example, BOOL EnumSystemLanguageGroups(
LANGUAGEGROUP_ENUMPROC pLangGroupEnumProc, // callback function
DWORD dwFlags, // language groups
LONG_PTR lParam // callback parameter
);

LANGUAGEGROUP_ENUMPROC is retrieved from another function called EnumLanguageGroupsProc.
When I try, using the headerfiles needed and kernel32.lib I come to the conclusion that
It may not exist anymore. Cause it doesn't recognize it.

Could you maybe help med with some example how to implement the different parameters, so
that I can understand what I'm doing wrong.

Thanks!

David Crow8-Jun-05 2:11

8-Jun-05 2:11

Hachaso wrote:
I've compared and can't find any difference that would solve the problem.

I provided you two different links. They are completely different.

Hachaso wrote:
LANGUAGEGROUP_ENUMPROC is retrieved from another function called EnumLanguageGroupsProc.

Huh? LANGUAGEGROUP_ENUMPROC is a typedef from winnls.h.

Hachaso wrote:
Could you maybe help med with some example how to implement the different parameters, so
that I can understand what I'm doing wrong.

BOOL CALLBACK EnumProc(
  LGRPID LanguageGroup,
  LPTSTR lpLanguageGroupString,
  LPTSTR lpLanguageGroupNameString,
  DWORD dwFlags,
  LONG_PTR  lParam
)
{
    return TRUE;
}
...
EnumSystemLanguageGroups(EnumProc, LGRPID_INSTALLED, 0);

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

Hachaso8-Jun-05 23:55

8-Jun-05 23:55

Hi!

Hope I'm not to much trouble.
I'm kind of new to this so thanks for all the help.

DavidCrow wrote:
Huh? LANGUAGEGROUP_ENUMPROC is a typedef from winnls.h.

I hope I understand this right:

How do I use this typedef?

LANGUAGEGROUP_ENUMPROC EnumProc; (like this ??)

Then declare the callback function:

BOOL CALLBACK EnumProc(
LGRPID LanguageGroup,
LPTSTR lpLanguageGroupString,
LPTSTR lpLanguageGroupNameString,
DWORD dwFlags,
LONG_PTR lParam
)
{
return TRUE;
}

Then send this to EnumSystemLanguageGroups:

EnumSystemLanguageGroups(EnumProc, LGRPID_INSTALLED, 0);

Is this how it is supposed to be used??

I read a remark in the page link you gave me;
This function can carry out any desired task. An application registers an EnumLanguageGroupsProc function by passing its address to the EnumSystemLanguageGroups function.

I'm really new to all this, so please explain in details.

Thanks!

David Crow9-Jun-05 2:05

How to share a variable between two classes?

9-Jun-05 2:05

Hachaso wrote:
How do I use this typedef?

LANGUAGEGROUP_ENUMPROC EnumProc; (like this ??)

Not necessary.

Hachaso wrote:
Is this how it is supposed to be used??

Yes, just like the code snippet I provided.

"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

fanlovefan2-Jun-05 21:02

fanlovefan

2-Jun-05 21:02

How to share a variable between two classes?

Please give me a answer.

Thank you very much!

Cedric Moonen2-Jun-05 21:30

Cedric Moonen

2-Jun-05 21:30

Could you be a little bit more specific ? What you mean exactly by sharing ?? Because you can have a lot of interpretations to that...

rammle2-Jun-05 21:30

rammle

2-Jun-05 21:30

I would just use pointers from one class to the other. Then you can easily work on the other class' variables.
Or point to a common structure or something like this. Wink | ;)

Bob Stanneveld2-Jun-05 22:03

Bob Stanneveld

2-Jun-05 22:03

If you mean that you want to share a variable among several instances of the same class, just make the variable (I assume that it is a member variable of the class) static..

Behind every greak black man...
... is the police. - Conspiracy brother

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