.定义一个CPU类，包含等级（rank）、频率（frequency）、电压（voltage）等属性，有两个公有成员函数run、stop。其中，rank为枚举类型CPU_Rank,定义为enum CPU_Rank{P1=1,P2,P3,P4,P5,P6,P7}，frequency为单位是MHz的整型数，voltage为浮点型的电压值。观察构造函数和析构函数的调用顺序.

#include <iostream>
using namespace std;
enum CPU_Rank{P1=1,P2,P3,P4,P5,P6,P7
};
class CPU
{
public:
CPU(CPU_Rank newrank=P1,int newfrequency=0,float newvoltage=0.0)
:rank(newrank),frequency(newfrequency),voltage(newvoltage)
{
cout<<"成功调用构造函数"<<endl;
cout<<"等级："<<rank<<endl;
cout<<"频率："<<frequency<<endl;
cout<<"电压：" <<voltage<<endl;
}
void run();
void stop();
~CPU(){
cout<<"成功调用析构函数"<<endl;
}
private:
CPU_Rank rank;
int frequency;
float voltage;
};
inline void CPU::run()
{
cout<<"cpu运行"<<endl;
}
inline void CPU::stop()
{
cout<<"cpu停止"<<endl;
}
int main()
{
CPU cpu(P3,60,220);
cpu.run();
cpu.stop();
return 0;
}