C / C++ / MFC

Re: error: expected unqualified-id before numeric constant

23-Apr-18 6:42

This is a linker error, not a compiler error. You have a definition of font_vga_8x8 in more than one source module. So although that looks OK to the compiler, when you link the object modules together the linker gets confused.

Vaclav_23-Apr-18 8:11

Re: error: expected unqualified-id before numeric constant

23-Apr-18 8:11

Thanks.
Good call, I tend to forget to disable unused source files!
Back to drawing board.

Vaclav_23-Apr-18 13:36

Re: error: expected unqualified-id before numeric constant

23-Apr-18 13:36

Well - I did try to cheat and renamed the offending variable.
Still same error - multiple definitions. Then I recall something about initializing struct as globals or something to that matter.
So I changed the struct to "static " and the error went away.
Why?
The #include file is global - not part of the class.

Richard MacCutchan23-Apr-18 21:05

Re: error: expected unqualified-id before numeric constant

23-Apr-18 21:05

The problem is not specific to struct types, but any variable. If a variable has global scope, i.e. it is declared outside of any method, then it is externally defined by default. That means its name is known to the linker. If it is declared static then it is internal to the compilation unit that contains it, and its name will not be visible to the linker. So if the linker encounters multiple variables with the same name it cannot decide how to link them correctly.

Vaclav_25-Apr-18 3:42

Re: error: expected unqualified-id before numeric constant

25-Apr-18 3:42

Ok, so if I put the struct declaration / definition as class variable it should work without being declared as static , right?

Would that defeat the purpose of #include in general?
This "font definitions" came from other application, not my original code.

Richard MacCutchan25-Apr-18 4:59

Obtaining a COM pointer in a C # ActiveX control inside an MFC ActiveX control

25-Apr-18 4:59

Sorry those three statements don't make much sense. The general way of handling situations like yours is to have the definition of the struct in a header file that multiple source modules can then include. Each source module would then declare an instance of the struct in what ever location they required, but not as a global. Having said that, there may be cases where declaring such a variable as global is the right thing to do, as its contents are shared between different modules. Only you (the application designer) can decide which is the right option.

SoulToMind20-Apr-18 20:48

SoulToMind

20-Apr-18 20:48

I have added a C # ActiveX control inside an MFC ActiveX control. How do I get the Com Interface for the added C # ActiveX control?

Error when printing

Erich Ruth20-Apr-18 5:51

Erich Ruth

20-Apr-18 5:51

I have a small program. I compile the executable. If I find the executable
and double click on it, everything works fine. I can print, print preview; all is
well.

If within visual studio I hit the green triangle to run the executable and then I
try to print or print preview, I get an error in this code:

inline void* CThreadSlotData::GetThreadValue(int nSlot)
{
EnterCriticalSection(&m_sect);
ASSERT(nSlot != 0 && nSlot < m_nMax);
ASSERT(m_pSlotData != NULL);
ASSERT(m_pSlotData[nSlot].dwFlags & SLOT_USED);
ASSERT(m_tlsIndex != (DWORD)-1);
if( nSlot <= 0 || nSlot >= m_nMax ) // check for retail builds.
{
LeaveCriticalSection(&m_sect);
return NULL;
}

CThreadData* pData = (CThreadData*)TlsGetValue(m_tlsIndex);
if (pData == NULL || nSlot >= pData->nCount)
{
LeaveCriticalSection(&m_sect);
return NULL;
}
void* pRetVal = pData->pData[nSlot];
LeaveCriticalSection(&m_sect);
return pRetVal;
}

It breaks at LeaveCriticalSection(). Im really perplexed as to why this error has arisen
and what to do to get it to go away. If you have any insight, please let me know.

[REPOST] Error when printing

Richard Deeming20-Apr-18 6:01

Richard Deeming

20-Apr-18 6:01

You have already posted this:
Print causes in afxtls.cpp - Managed C++/CLI Discussion Boards[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Re: [REPOST] Error when printing

Victor Nijegorodov20-Apr-18 6:48

How to use constructor list passing an array

20-Apr-18 6:48

Richard, but there was just a wrong forum!
Therefore (I think) he has reposted the question here....

Re: Error when printing

David Crow20-Apr-18 6:12

David Crow

20-Apr-18 6:12

Erich Ruth wrote:
...I get an error in this code:

What error?

Erich Ruth wrote:
It breaks...

What does that mean, exactly?

Could it be a difference between release vs. debug mode? Have you stepped into LeaveCriticalSection() to see what is happening (e.g., fired assertion)?

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Re: Error when printing

Erich Ruth20-Apr-18 7:49

Erich Ruth

20-Apr-18 7:49

When I say it breaks, that means it pops up a box that says:

"Unhandled exemption x 0x777f6a73 in MultiScreen.exe: 0xC0000005: Access
violation reading location 0xfeeefefa.

and then I have Break or Continue. I hit Break and it shows me this code:

inline void* CThreadSlotData::GetThreadValue(int nSlot)
{
	EnterCriticalSection(&m_sect);
	ASSERT(nSlot != 0 && nSlot < m_nMax);
	ASSERT(m_pSlotData != NULL);
	ASSERT(m_pSlotData[nSlot].dwFlags & SLOT_USED);
	ASSERT(m_tlsIndex != (DWORD)-1);
	if( nSlot <= 0 || nSlot >= m_nMax ) // check for retail builds.
	{
		LeaveCriticalSection(&m_sect);
		return NULL;
	}

	CThreadData* pData = (CThreadData*)TlsGetValue(m_tlsIndex);
	if (pData == NULL || nSlot >= pData->nCount)
	{
		LeaveCriticalSection(&m_sect);
		return NULL;
	}
	void* pRetVal = pData->pData[nSlot];
	LeaveCriticalSection(&m_sect);
	return pRetVal;
}

and its pointing to

LeaveCriticalSection(&m_sect);

which is the 2nd to last line.

Re: Error when printing

Randor 20-Apr-18 20:26

Randor

20-Apr-18 20:26

Hi,

0xfeeefeee is a magic number[^] used by the debug heap for marking memory that's been freed. So it looks like the data at pData->pData[nSlot]; has already been freed by the time you try to read it.

This probably means that the bug also exists in your 'Retail build'. A retail build with a normal heap may happily read garbage data and keep on going.

You can probably debug this by setting up a memory watch[^] for &pData->pData[nSlot];

Best Wishes,
-David Delaune

Vaclav_20-Apr-18 5:45

20-Apr-18 5:45

Could somebody please correct this code for me ?

I am trying to pass char array to a constructor and USE
LIST to initialize the class variable.

I can do single char - USING LIST - no problem, I can pass a variable and copy it to class variable.
I am trying to learn more about using LIST AND I am hopelessly lost
how to pass a char array - preferably "by pointer".
I have tried all kinds of syntax combinations, samples etc. but I really need some help.
Appreciate any inputs.

<pre lang="c++">
// passing an array of char
char array[16];

public:
CLASS_SPI_NEW(char array): array(array)
{

}</pre>

Victor Nijegorodov20-Apr-18 6:45

20-Apr-18 6:45

Vaclav_ wrote:
<pre lang="c++">

// passing an array of char
char array[16];
public:
 CLASS_SPI_NEW(char array): array(array)
{

}&lt;/pre&gt;</blockquote>
Did you probably mean
C++
CLASS_SPI_NEW(char* array): array(array)

Vaclav_20-Apr-18 8:45

20-Apr-18 8:45

Thanks for the suggestion , here is what I did and it works.

Two more questions
The array actually gets filed with 12 characters and I have "sized" it for two.

This "list constructor " code syntax have no "prototype", but it works.

<pre> char *array = " ";
int channel;
long speed;
int mode;
C_SPI_NEW(char *array, int channel, long speed, int mode )
: array(array), channel(channel), speed(speed), mode(mode)
{
#ifdef DEBUG
cout << "\033[1;31mConstructor \033[0m\n";
cout <<" device " << array <<endl;
cout <<" channel " << channel << endl;
cout <<" speed " << speed << endl;
cout <<" mode " << mode << endl;
cout << " function " << __FUNCTION__ << endl;
cout << " line " << __LINE__ << endl;
#endif

}</pre>

Victor Nijegorodov20-Apr-18 11:13

20-Apr-18 11:13

Is there some very important reason to use plain char array instead of std::string or MFC CString class?

Vaclav_20-Apr-18 11:25

20-Apr-18 11:25

Yes, but it is complicated.
Since you asked-
I am using PC to remotely compile C++ code for Raspberry Pi.
No MFC needed.
My OS is Ubuntu and my IDE is Eclipse. I have no problem using String on PC locally, but the OS on Raspberry Raspbian complains about wrong version of some library.
When I check the version in question it is current.
Instead of trying to figure out something over my head I simply do no use String.
My application is pretty much "low level bits" communication anyway.
Problem solved.

linking issue

tasumisra16-Apr-18 6:51

tasumisra

16-Apr-18 6:51

Hello All,

I have C++ dll, that has some exposed functionality using Def files, among all those CPP files there is one Cpp (Lets call it "Generator.cpp") files that dosnt gets compile normally but it is used to generate supporting C++ file that is exposed in Def files.(some how...some developer thought process, Legacy code)

the Generator.cpp looks like this

#ifdef _USRDLL
#pragma comment(linker, "/EXPORT:GenerateFiles=?GenerateFile@@YGJPAUHWND__@@PAUHINSTANCE__@@PADH@Z")
#endif

__declspec(dllexport) HRESULT __stdcall GenerateFiles(HWND hwnd,HINSTANCE hinst,LPSTR lpCmdLine,int nCmdShow)
{
/// some code to generate CPP files exposing by the DLL
}

can some body help what commandline parameter i should pass so that possible EXPORT can happen and CPP file would be generated.

vikas da

Re: linking issue

Victor Nijegorodov16-Apr-18 21:39

16-Apr-18 21:39

Please, don't crosspost!
You already started the similar thread in ATL / WTL / STL Discussion Boards

Re: linking issue

Richard MacCutchan17-Apr-18 0:33

How to write more that ONE data byte into ioctl file?

17-Apr-18 0:33

I already explained that we do not have enough information. We have no idea what this code is for or how it is accessed from other applications.

Vaclav_11-Apr-18 14:47

Re: How to write more that ONE data byte into ioctl file?

11-Apr-18 14:47

This may be too silly to ask here , really a hardware question , but I am stuck.

I am using ioctl to write to I2C device - LCM1602.
This device uses PCF8574 "I2C interface chip" to connect to HD44780 Hitachi LCD controller in 4 bits mode .
Setting the HD447890 into 4 bit mode is well documented, but..

After the HD44780 is set into 4 bit mode further configuration need to be set using TWO (I2C sends 8 bits but only 4 bits are valid ) data "packets" after the single I2C address is send.
I have this single address plus data working and cannot figure out HOW to
add another "buffer" so I can send TWO 8 bits words.
The I2C spec requires to wait for ACK after the first 8 bit data is send, so I just cannot add the data into single buffer.

PLEASE - THE ATTACHED CODE IS WORK IN PROGRESS, REDUNDANT ETC , BUT IT WORKS!
ANY INAPPROPRIATE COMMENTS ON IT WILL BE IGNORED AND ARE NOT WELCOMED.

However, I'll appreciate any suggestions on how to send
ONE address byte and multiple data bytes in I2C format.
Thanks.

<pre lang="c++">
// original expanded
// write directly to expander using ioctl file descriptor
// and plain write(fd,data,#)
// parameters
// int file file descriptor
// char data data to write
// int NumberOfCharacters to write
// return 0 when actual # of characters match NumberOfCharacters
int CLASS_LCM1602::expanderWrite(
int file,
char data,
int NumberOfCharacters) {
#ifdef DEBUG
//cout << "\033[1;31mint C_I2C::TestFunction(int a)\033[0m\n";
cout << "*** TRACE file " << __FILE__ << endl;
cout << " Enhanced function " << __FUNCTION__ << endl;
cout << " line " << __LINE__ << endl;
#endif
int NumberOfCharactersWritten;
// why NOBACKLIGHT during initialization - too fast to see anyway (?)
char buffer = data; // | LCD_BACKLIGHT;
//buffer = 0;
//while (1)
{
#ifdef DEBUG
cout << " buffer cast " << (static_cast<int>(buffer) & 0xFF) << endl;
cout << " buffer HEX cast " << hex << buffer << endl;
cout << " buffer + " << hex << +buffer << endl;

cout << " function " << __FUNCTION__ << endl;
cout << " line " << __LINE__ << endl;
#endif
//sleep(5);
}

// NumberOfCharacters defaults to 1

NumberOfCharactersWritten = write(file, &buffer, NumberOfCharacters);

// check characters written
if (NumberOfCharacters == NumberOfCharactersWritten) {
#ifdef DEBUG
cout << "Success NumberOfCharacters written " << NumberOfCharacters
<< endl;
#endif
//exit(1);
return 0;
} else {
cout << "\033[1;31mFailed expanderWrite\033[0m\n"; // failed
return -1;
}

}

</pre>

Richard MacCutchan11-Apr-18 21:26

Re: How to write more that ONE data byte into ioctl file?

11-Apr-18 21:26

Vaclav_ wrote:
ANY INAPPROPRIATE COMMENTS ON IT WILL BE IGNORED AND ARE NOT WELCOMED.

Well that really encourages people to want to help you.

Victor Nijegorodov11-Apr-18 22:06