设计一个名为Fan的类，表示一个风扇。这个类包含：一个名为speed的int型数据，一个名为on的bool型数据域，一个名为radius的double型数据域，一个名为color的字符型数据域，一个无实参构造函数，创建一个默认的风扇。-Design a class named Fan, said a fan. This class includes: a data type int called speed, called on the bool type data field, called the radius of a double-type data field, a character named color data field, a no-argument constructor, Create a default fan.