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I'm having a very strange problem with a third party dll. When I try to use this dll in my program an exception is thrown even before WinMain is called, yet other programs use it without any problems.
Eventually, I narrowed it down. If any program uses the dll and also calls a certain Windows function (for example SHGetSpecialFolderPath, or timeGetTime) then the the exception happens.
This problems seems really bizarre to me. Does anyone know what could be causing it?
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You stated that the exception is thrown before your WinMain(). Statically linked dlls are loaded by windows for your executables and DLLs. The DllMain() of statically linked DLLs execute eralier than the main of the module (dll or exe) that actually uses the DLL. I would suspect that something is screwed up in your 3rd party DLL and it might be sensitive to DLL loading order. If you exe uses SHGetSpecialFolderPath() from shell32.dll and the 3rd party library also uses a function from shell.dll then the loading of shell32.dll might happen before or after the loading of your 3rd party depending on whether your program loads shell32.dll or the 3rd party first. However this whole situation seems to be totally screwed up for me. Try to set a breakpoint on "module load" events and debug the loading order of your DLLs, maybe you find out something useful. Try to search for the exception code too in google.
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Post a call stack. Always post a call stack!
Steve
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Ok:
> ntdll.dll!7c967406()
[Frames below may be incorrect and/or missing, no symbols loaded for ntdll.dll]
ntdll.dll!7c940e5a()
ntdll.dll!7c918790()
ntdll.dll!7c90e457()
libGLESv2.dll!00360062()
I doubt if that's any use though
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The one useful bit is the last line that suggests the problem started in libGLESv2.dll. Assuming this is the 3rd party library you should contact the author(s) for help.
One of these days I'm going to think of a really clever signature.
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Yeah, I already contacted them, but no answer. I think I'm just going to give up and use an alterate library.
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Use a symbol server when getting a stack trace.
Steve
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ed welch wrote: yet other programs use it without any problems.
That suggests along with your other responses that something about the build, rather than usage, is different.
There are different ways of setting up the runtime environment based on linker options.
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no, I comfirmed that it's not any compile or link option
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hi !!!!! in my project am going to use prediction algorithm for predicting the rail track allocation for incoming trains in a station.. any one please help in finding the algorithm or the
C code .
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Without knowing what the algorithm is it's a bit difficult to guess what the C code is. You say that you are going to use this algorithm so maybe you could provide details.
One of these days I'm going to think of a really clever signature.
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Google is your friend. Moreover, we have a 'Algorithms' forum here at CodeProject.
Veni, vidi, vici.
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How about reading the time table? I've found it to be surprisingly efficient at predicting what track each train would be incoming at. 
Seriously:
1. go to the 'algorithms' sub forum. Until you have an algorithm, there is no C/C++ question to solve.
2. specify precisely the input you have and the output you want. Without that information it is impossible to find an algorithm. For all I know now, my answer above may in fact be sufficient (although I doubt it)
3. use the internet search engine of your choice and search for similar projects. You probably won't find exactly what you need, but if you see something similar, you can try and adapt it to your project, or ask for help in doing so.
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Hi,
I have a dialog box. I have 10 buttons on that dialog box. I am using CSkinButton class to use images for those buttons. I want to provide scrollbar to the dialog box dynamically. For example, if I use 6 buttons, will fit the size of the dialog box. If I want to use 10 buttons, then vertical and horizontal scroll bar should appear on the dialog box automatically. As I using Images (Bitmaps) for buttons, scroll bar doesn't appear automatically.
I have tried to set the property of the dialog box for scroll bar. It doesn't work.
Anybody have anny idea regarding this.?
Please let me know if you have any doubt in understanding the above questions.
Regards,
Mbatra
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This should be a good start.[^]
Can I advise you to re-think your UI to not have to have scrollbars AT ALL ? It is quite counter-intuitive for users to have to scroll in a dialog to be able to see buttons.
Max,
Watched code never compiles.
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Hi,
I want to create an MFC MDI Application, which is used to draw engineering 2D drawing. A similar one to Auto CAD 2D software.
Can anyone of you suggest us the best open source library which we can use to implement 2D mfc drawings.
I know some of libraries like OpenGL, DirectX but i am not sure a) whether we can use these libraries to create 2D drawings. b) whether we need to purchase these libraries as we are developing a commercial application. c) there may be better libraries available for 2D drawing and it may be for free.
Thanks,
Regards
Maha
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OpenS-CAD, a simple 2D CAD application [here].
2D Drawing - Doc/View architecture [here].
CadLib for creating DXF(Drawing Interchange Format) files [here].
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We have in many places in our code things like :
(pseudo-code)
if ( string.compare(A) == 0 )
{
}
else if ( string.compare(B) == 0 )
{
}
else if (string.compare(C) == 0 )
{
}
else if (....)
{
}
else
{
}
I know that we cannot use switch cases for strings, but is there a better way to do cascading If comparisons on strings ?
(This is not urgent  ).
Thanks.
Max.
Watched code never compiles.
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Two optimization tricks:
1. You store the possible values (A, B, and C, ...) in a sorted array and you search your string in that array with binary halving. Alternatively you can store A,B,C in one of these: map/hashmap/search tree.
2. If you opt for using == and/or != with if/else then you can speed up these operations for strings by storing the hash value for each string. When you compare two strings you first compare the hash values. If the hash is different then you have your result immediately (false for == and true for !=). If the hash for the strings is different then you have to perform the actual comparison on the strings. I usually write a special string class that contains the hash as well. It has the drawback that the hash must be updated before comparisons if the string has been modified since the last hash calculations. Sometimes purely written old legacy code can be tweaked very well with this trick. Use djb2 to hash your strings, for unicode use utf8: http://www.cse.yorku.ca/~oz/hash.html[^]
EDIT: Just noticed my answer isn't exactly the what you are searching for, but I think there is no fine solution to your problem. This problem is similar to the typical factory patterns that are used to instantiate a specific type by name:
template <typename T>
class StringSwitch
{
public:
void SetInstance(T* instance)
{
m_Instance = instance;
}
void RegisterHandler(const std::string& s, void (T::*handler)())
{
m_SwitchTable[s] = handler;
}
bool PerformOperation(const std::string& s)
{
auto it = m_SwitchTable.find(s);
if (it == m_SwitchTable.end())
return false;
(m_Instance->*(it->second))();
return true;
}
private:
std::map<std::string,void(T::*)()> m_SwitchTable;
T* m_Instance;
};
class BlahBlah
{
public:
BlahBlah()
{
m_SwitchTable1.SetInstance(this);
m_SwitchTable1.RegisterHandler("A", &BlahBlah::StringA);
m_SwitchTable1.RegisterHandler("B", &BlahBlah::StringB);
m_SwitchTable1.RegisterHandler("C", &BlahBlah::StringC);
}
void StringA()
{
printf("%s\n", __FUNCTION__);
}
void StringB()
{
printf("%s\n", __FUNCTION__);
}
void StringC()
{
printf("%s\n", __FUNCTION__);
}
void Run()
{
m_SwitchTable1.PerformOperation("B");
}
private:
StringSwitch<BlahBlah> m_SwitchTable1;
};
int main()
{
BlahBlah b;
b.Run();
return 0;
}
Your refactorized if/else is inside BlahBlah::Run()
modified 23-Aug-12 11:09am.
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You can choose to store strings in buffers of length 4*n. That way you can compare two DWORD vectors. It will be case sensitive, but faster than strcmp. You can also use switch on the first DWORD, but !!!ONLY!!! if no two strings share the same 4 bytes at the begining.
Also, Pascal strings.
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Triky solution ! Got my 5 !
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A minor optimization would be to order your comparisons from most-likely-to-match down to least-likely-to-match. That way, your if test block is exited as soon as possible.
"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
"Show me a community that obeys the Ten Commandments and I'll show you a less crowded prison system." - Anonymous
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Maximilien wrote: t is there a better way to do cascading If comparisons on strings
Where "better" means what?
If you just don't like looking at the code then you could do code generation.
If there is a actual profiled performance problem traced to this then you can used collected data to order the comparisons with most used first and least used last. Depending on the number of strings, and the data in the strings other optimizations are possible.
One solution again dependent on data and usage is to parse the input, when first received, into a value such as an enumeration and only use that in the rest of the code.
If there is a lot of churn with these then generation can still help but dynamic collections might solve that, with care. However such solutions might not be as performant and add some level of complexity.
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I give you a little solution (MFC way):
CStringList List;
List.AddTail(A);
List.AddTail(B);
List.AddTail(C);
List.AddTail(D);
....
if(NULL != List.Find(string))
{
}
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