Qt之QSpinBox&QDoubleSpinBox

//顯示整數
    QSpinBox *spin = new QSpinBox(this);
    spin->setMinimum(10);
    spin->setMaximum(300);
    spin->setPrefix("$ ");
    spin->setValue(200); //設置默認值，必須在10-300之間，不然離10進就是10，離300進就是300
    spin->setGeometry(10, 30, 100, 30);

    QDoubleSpinBox * doublespin = new QDoubleSpinBox(this);
    doublespin->setMinimum(10.0);
    doublespin->setMaximum(300.0);
    doublespin->setValue(50.5);
    doublespin->setSuffix(" mm");
    doublespin->setGeometry(30 + 110, 30, 100, 30);
    
    //經常使用的信號：valueChanged(int)，valueChanged(double)