关于布局问题，2种布局，第一个种显示不出can这个实例。第二种分布能显示
wid::wid(QWidget *parent):QWidget(parent)
{
resize(400,400); QPushButton *quit = new QPushButton("Quit",this); QSlider *slider = new QSlider(Qt::Horizontal ); QLCDNumber *lcd = new QLCDNumber; cannon *can = new cannon(this); QVBoxLayout *layout_left=new QVBoxLayout; layout_left->addWidget(quit); layout_left->addWidget(lcd); layout_left->addWidget(slider); QHBoxLayout *layout =new QHBoxLayout; layout->addLayout(layout_left); layout->addWidget(can); this->setLayout(layout); }
wid::wid(QWidget *parent):QWidget(parent){ resize(400,400); QPushButton *quit = new QPushButton("Quit",this); QSlider *slider = new QSlider(Qt::Horizontal ); QLCDNumber *lcd = new QLCDNumber; cannon *can = new cannon(this); QVBoxLayout *layout_left=new QVBoxLayout; layout_left->addWidget(quit); layout_left->addWidget(lcd); layout_left->addWidget(slider); layout_left->addWidget(can); this->setLayout(layout_left);}
