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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.
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Thanks.
Good call, I tend to forget to disable unused source files!
Back to drawing board.
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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.
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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.
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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.
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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.
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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? 
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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.
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Richard, but there was just a wrong forum!
Therefore (I think) he has reposted the question here....
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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)?
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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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 )
{
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.
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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
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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>
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Vaclav_ wrote: <pre lang="c++">
// passing an array of char
char array[16];
public:
<b>CLASS_SPI_NEW(char array): array(array)</b>
{
}</pre></blockquote>
Did you probably mean
CLASS_SPI_NEW(char* array): array(array)
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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>
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Is there some very important reason to use plain char array instead of std::string or MFC CString class?
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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.
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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)
{
}
can some body help what commandline parameter i should pass so that possible EXPORT can happen and CPP file would be generated.
vikas da
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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.
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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 <b>4 bits mode</b> .
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);
}
// <b>NumberOfCharacters defaults to 1</b>
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>
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Vaclav_ wrote: ANY INAPPROPRIATE COMMENTS ON IT WILL BE IGNORED AND ARE NOT WELCOMED.
Well that really encourages people to want to help you.
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Vaclav_ wrote:
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.
Hmm,
don't you mind such a "thesis" together with unformatted code looks like gross unrespect to guys you ask to help?  
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You do it like with any write operation to a file descriptor by passing a buffer and it's size:
char buf[2];
buf[0] = data & 0x0f;
buf[1] = data >> 4;
write(file, buf, 2);
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