Widget::Widget(QWidget *parent) : QWidget(parent),ui(new Ui::Widget)
阿新 • • 發佈:2018-11-28
#include <QCoreApplication> #include <iostream> using namespace std; class Base { public: Base() :m_num(0){ cout << "this is Base()" << endl; cout<<m_num<<endl; } Base(int val):m_num(val){ cout << "this is Base(int val)" << endl; } void fun(int a); private: int m_num; }; void Base::fun(int a) { m_num=a; } class BaseChild: public Base { public: BaseChild(){ cout << "this is BaseChild()" << endl; } BaseChild(int val); void fun(int a,int b); /*BaseChild(int val): Base(val){ cout << "this is BaseChild(val)" << endl; }*/ private: int n_num; }; BaseChild::BaseChild(int val) : Base(val),n_num(val) { cout<<"sdfas"<<endl; } int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); BaseChild child1(5); // BaseChild child2(5); return 0; return a.exec(); }
http://www.cnblogs.com/findumars/p/9231742.html
https://blog.csdn.net/weibo1230123/article/details/75348785
https://blog.csdn.net/Pg_dog/article/details/70224675
BaseChild是類, ::是作用域,::後面的BaseChild(int val)是建構函式,:後面的Base(val)是指定基類的建構函式,不明確指定的話是預設建構函式,n_num(val) 是對BaseChild類裡面的成員變數做初始化。
將上面這句話和Widget::Widget(QWidget *parent) : QWidget(parent),ui(new Ui::Widget)作比較,便可以理解。