Qt编程基础 hello QT

#include

#include 

int main(int argc, char *argv[])

{

    int QExitCode = 0;

    /** 创建一个应用程序对象来管理程序范围内的资源 */

    QApplication app( argc, argv );

    /** info: widget and  MainWindow

        a widget is a visual element in a user interface

        most application use a QMainWindows or a QDialog as the application Window,

        but Qt is so flexible that any Widgets can be a windows .

        Qt's widgets emit signals to indicate that a user action or

        a change of state has occurred .

     */

    QPushButton *button = new QPushButton("Quit");

    button->resize( 100, 30 );

    /** Qt的 widgets 通过发射信号来指出用户的行为或状态发生改变

        一个信号可以和一个函数相连接,称为solt,当single emitted时,

        solt 函数自动执行  */

    QObject::connect(button,SIGNAL(clicked()),&app ,SLOT(quit()));

    /** widgets 被创建后默认为隐藏,因此我们可以在显示它之前对它进行定制,从而避免了闪烁 */

    button->show();

    /**  再这里,程序将控制权传递给QT,进入事件循环,等待用户输入 */

    QExitCode =  app.exec();

    delete button;

    return QExitCode;

}