第一种写法,字符串拼接,用的VC,单纯C++以前的写法,没有用Qt自带的QString操作,一直以为没有问题,这次使用时,经常会内存泄漏,没有明白。 查了一下:sprintf不是类型安全的,在执行的时候,它不会检查数组边界。所以当给其格式化一个比其大小还长的字符串时,就导致缓冲区溢出。 还找到一个函数:sprintf_s()是sprin...
Anything that has a constructor or needs to run code to be initialized cannot be used as global object in library code, since it is undefined when that constructor/code will be run (on first usage, on library load, before main() or not at all). Even if the execution time of the init...
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1. c++小问题has no member named ''XXX‘(24849) 2. c++软件开发第三方库大全(19509) 3. QT学习笔记-29.使用QT HTTP下载网络文件(13005) 4. gcc之declaration does not declare anything解决方案(11841) 5. QT学习笔记-35:QTableWidget动态增加行的方法(11772) 评论排行榜...
We also forward declare the two classes that our widget will be built from.We include the Q_OBJECT macro since this is required for classes that declare signals or slots. The Q_ENUMS declaration is used to register the Mode enumeration. Our widget has two properties, mode, to store ...
Q_CHECK_PTR does nothing if QT_NO_DEBUG was defined during compilation. Example: int *a; Q_CHECK_PTR(a = new int[80]); // WRONG! a = new (nothrow) int[80]; // Right Q_CHECK_PTR(a); See also qWarning() and Debugging Techniques. Q_DECLARE_TYPEINFO ( Type, Flags ) You can...
To declare a property, use the Q_PROPERTY() macro in a class that inherits QObject. Q_PROPERTY(type name (READ getFunction [WRITE setFunction] | MEMBER memberName [(READ getFunction | WRITE setFunction)]) [RESET resetFunction] [NOTIFY notifySignal] [REVISION int | REVISION(int[, int])...
This will create a global variable calledmyObjectin the script environment. The variable serves as a proxy to the underlying C++ object. Note that the name of the script variable can be anything; i.e., it is not dependent uponQObject::objectName(). ...
In the following example, we declare a property of the enumeration typePrioritythat is also calledpriorityand has a get functionpriority()and a set functionsetPriority(). classMyClass :publicQObject{ Q_OBJECT Q_PROPERTY(Priority priority READ priority WRITE setPriority) Q_ENUMS(Priority)public:enu...
If your geometry is simple and does not require interactive and hierarchical features, you should use QPainter directly. Use QGraphicsView for anything complex and interactive. DescriptionScreenshot Movable Image - We'll make a scene, and the scene will be shown with the elements we'll be addi...