I have an interesting question about C++ pointers. You probably will think that I have to change my design, and avoid doing what I am doing, and you are probably right. But let's assume that I have a good reason to do it my way. So this is the situation. I have a C++ class TestClass, and I have a pointer A of this type: TestClass* A =...
I have a loop to take in images from a high speed framegrabbger at 250fps. /** Loop processes 250 video frames per second **/ while(1){ AcquireFrame(); DoProcessing(); TakeAction(); } At the same time, I would like the user to be able to monitor what is going on. The user only needs to see images at around 30 fps (or less). Ho...
This doesn't work: unsigned char foo; foo = 0x123; sprintf("the unsigned value is:%c",foo); I get this error: cannot convert parameter 2 from 'unsigned char' to 'char' ...
I have a c++ dll which I need to debug. Due to the circumstances in which I am using the dll, I am unable to debug it via the calling application. So, I created a try -catch, where the catch writes the exception to a file. The line which needs to be debugged involves imported classes from a 3rd party dll, so I have no way of knowing wh...
Hi, I'm using a QMenu as context menu. This menu is filled with QActions. One of these QActions is checkable, and I'd like to be able to check/uncheck it without closing the context menu (and having to re-open it again to choose the option that I want). I've tried disconnecting the signals emitted by the checkable QAction with no luck....
In Qt docs EnterEditFocus is a event about an editor widget gaining focus for editing but using Qt 4.5.3 the compilation fails with ‘EnterEditFocus’ is not a member of ‘QEvent’. What's wrong? ...
I'm trying to debug a server I wrote with gdb as it segfaults under very specific and rare conditions. Is there any way I can make gdb run in the background (via quiet or batch mode?), follow children (as my server is a daemon and detaches from the main PID) and automatically dump the core and the backtrace (to a designated file) once ...
We have found that HP's printer drivers fail to handle PlgBlt()s properly for many of their printers. Our intention is to handle any orthogonal rotations ourselves, and only have the printer handle scale and translation (which it seems to handle correctly). I have a 2D matrix available to me at the point in code where I am about to "dr...
I have an interface std::string get_string(Source const &s, std::string const &d); int get_int(Source const &s, int const &d); bool get_bool(Source const &s, bool const &d); which I'd like to change to template<class T> T get(Source const &s, T const &d); But there's no sensible base template, so the actual base definition is a leg...
When passing argument to main() in a C or C++ application, will argv[0] always be the name of the executable? Or is this just a common convention and not guaranteed to be true 100% of the time? ...
Hello, I need to design a Task Manager, not like windows task manager, but a more generic one. like "i should take my kid to school" kind of task. So, i need to design an appropriate scalable gui ? (in the future there might be hundreds of tasks) Can someone suggest a place/app to look at ? in addition, and on related subject : I op...
I would like a process to always run at the user level. Either when it is launched by the installer (custom, not msi), which runs as at the administrator level, or when a user logs on. Looking around, I'm not sure this is possible. ...
I have a function which reads in a character, one byte at a time, through the serial port. After these bytes are collected, they are passed to a method to process the bytes and message. I know how to fix the problem (fix is below), but why do my bytes get truncated when I don't perform the fix? unsigned char dpBuf[255]; ... // Preten...
What accounts for the added execution time of the first data set? The assembly instructions are the same. With DN_FLUSH flag not on, the first data set takes 63 milliseconds, the second set takes 15 milliseconds. With DN_FLUSH flag on, the first data set takes 15 milliseconds, the second set takes ~0 milliseconds. Therefore, in both...
Trying to find a "simple to use" safe_bool idiom/implementation, I've ended up with my own. Q: Is this implementation correct? template <typename T> class safe_bool { protected: typedef void (safe_bool::*bool_type)() const; bool_type to_bool_type(bool b) const { return b ? &safe_bool<T>::safe_bool_true : 0; } private: ...
How does it work? (Explain it in terms of server, writes, GETs, values, whatever). DOes it work with Win32 apps? ...
I have a question about the following code: class MyClass : private boost::noncopyable { public: MyClass() {} virtual ~MyClass() {} } class OtherClass : private boost::noncopyable { private: MyClass* m_pMyClass; } My thoughts are that MyClass cannot be copied using construction or assignment. Using a virtual des...
I couldn't find anything regarding this on http://msdn.microsoft.com/en-us/library/bb982727.aspx. Maybe I could use '[^]+' to match everything but that seems like a hack? Thanks. ...
Hey, my friends and I are trying to beat each other's runtimes for generating "Self Numbers" between 1 and a million. I've written mine in c++ and I'm still trying to shave off precious time. Here's what I have so far, #include <iostream> using namespace std; bool v[1000000]; int main(void) { long non_self = 0; for(long i = 1; i...
It seems pretty clear that it is supposed to set things up. When exactly does it run? Why are there two brackets? Is __attribute__ a function? A macro? Syntax? Does this work in C? C++? Does the function it works with need to be static? When does __attribute__((destructor)) run? Example in Objective C: __attribute__((constructor)) s...