使用VC6打开考生文件夹下的工程test17_1，此工程包含一个源程序文件test17_1.cpp，但该程序运行有问题，请改正程序中的错误，使程序的输出结果如下：
Vehicle message
Car message
Vehicle message
源程序文件test17_1.cpp 清单如下:
#include ＜iostream.h＞
class vehicle

int wheels;
float weight;
public:
/***************** found *****************/
void message(void) cout＜＜"Vehicle message\n";
;
class car:public vehicle

int passenger_load;
public:
/***************** found *****************/
void message (void)cout＞＞"Car message\n";
;
class truck:public vehicle

int passenger_load;
float payload;
public:
int passengers(void)return passenger_load;
;
void main()

vehicle * unicycle;
unicycle=new vehicle;
/***************** found *****************/
unicycle.message()
delete unicycle;
unicycle=new car;
unicycle-＞message();
delete unicycle;
unicycle=new truck;
unicycle-＞message();
delete unicycle;