I had a need to dump some data I am getting from a real-time sensor network to a database and I choose MySQL - just because it is cheap and cheerful and will fit perfectly with what I am looking for. Now, I have never programmed for MySQL though I have used it in the past as a consumer (e.g. the backend of this blog). MySQL does expose a C API that one can use, but it seems quite arcane to use and does not quite conform to the C++ style (especially when using STL)....
When you try and compile some code and you get an error along the lines of invalid use of an incomplete type ‘whatever type’ then in most cases it means you need to include the header file where that type is displayed. For example I had the following events in my header file: 1 2 3 protected: void mousePressEvent(QGraphicsSceneMouseEvent *event); void mouseReleaseEvent(QGraphicsSceneMouseEvent *event); When when I tried to compile gave the following error: invalid use of incomplete type ‘struct QGraphicsSceneMouseEvent’...
Often you need to search through an array or list to find a specific element and of course you need this search to be as fast and efficient as possible. One of the best ways to do this is using a binary predicate function. A binary function is a function object (which are also called Functors ) and is any object which can be called as if it was a function....
If you are on Linux and want to print some code and also make it look pretty then check out a2ps (Any to postscript filter). Of course if you can avoid printing in the first place and saving paper and trees and make it greener that is ideal - however there are times that is not possible. I tried printing from CDT, but the printing options from CDT just looks plain ugly and big fonts and can spread over 10 pages for a simple code file (spanning 293 lines)....
I came across the Ten commandments of Programming while looking at a question on StackOverflow and I can’t believe I have not seen these before. I think every developer, lead, architect, dba, pm, whoever should print this out! 8-) Understand and accept that you will make mistakes. The point is to find them early, before they make it into production. Fortunately, except for the few of us developing rocket guidance software at JPL, mistakes are rarely fatal in our industry, so we can, and should, learn, laugh, and move on....
Here is a good example on why either you love C++ or hate it with such terse expression oriented code; I think its pretty cool. If you want to copy one string to another, one option can be something like this. 1 2 3 4 5 6 void mycopy(char *p, char *q) { int len = strlen(q); for(int i=0; i<=len; i++) p[i] = q[i]; } However this achieves the same thing as above and is more efficient:...
If you ever got an error something like [some-class] has initialiser but incomplete type, it basically means the compiler cannot understand the type and you need to add the include for it. 1 2 3 4 5 QPixmap pixmap(20,10); pixmap.fill(Qt::white); QPainter painter(&pixmap); QPen pen(Qt::blue); Take the code snipped above when you compile it you might get an error something along the lines of the following for line 4. ‘QPainter painter’ has initialiser but incomplete type...
If you are new to C++ then some of the compiler errors can be a bit confusing and daunting at first. For example if the compiler given you an expected primary-expression error (e.g. expected primary-expression before ‘.’ token), at face value it does not make sense. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 void RGBViewer::accept() { QMessageBox::information(this, "Button Clicked", "You clicked OK", QMessageBox::Ok); QColor color = QColor(Ui_RGBViewerClass....
As promised earlier, the Sanbox is up - go give it a whirl and let me know your thoughts. Also the code and release build of the World Clock are up there. Check it out and let me know what you think of it and also any bugs and feature enhancements you would like to see.