#include <iostream> const float pi = 3.14159; class Shape { public: virtual float getArea()//"virtual" couses, compilator { //have to find out, on which object return -1.0; //pointer points (base or derivative) } }; class Square: public Shape { public: Square(const float side): a(side){} void pureVirtualMethod(){} float getArea() { return a * a; } private: float a; }; int main () { Shape *shape; Square square(3); shape = □ std::cout<<square.getArea()<<std::endl; /*if in base class the getArea() method wasn't mark as virtual that following line will call method from base class(not derivative)*/ std::cout<<shape->getArea()<<std::endl; }
czwartek, 23 marca 2017
[C++]Virtual methods
piątek, 3 marca 2017
[C++][Qt]How to sort QComboBox.
combo->addItems(QStringList() << "B" << "C" << "A"); // "B","C","A" // for sorting you need the following 4 lines QSortFilterProxyModel* proxy = new QSortFilterProxyModel(combo); // <-- proxy->setSourceModel(combo->model()); // <-- // combo's current model must be reparented, // otherwise QComboBox::setModel() will delete it combo->model()->setParent(proxy); // <-- combo->setModel(proxy); // <-- // sort combo->model()->sort(0); // "A","B","C"
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