下面程序的执行结果是( )。
#include＜iostream＞
using namespace std;
class building
public:
building()
building(unsigned stories, float breadths, float lengths)
story = stories; breadth = breadths; length = lengths;
void getstory(void)
cout＜＜"story is:"＜＜story＜＜endl;
void getarea(void)
area = length*breadth*story;cout＜＜"area is:"＜＜area＜＜endl;
private:
unsigned story;
float length;
float breadth;
float area;
;
void main(void)
building b1,b2;building b3(10u,16.6,58.8);
b1.getstory();
b1.getarea();
b2.getstory();
b2.getarea();
b3.getstory();
b3.getarea();
A．story is:0
area is:0
story is:0
area is:0
story is:10
area is:9760.8
B．story is:null
area is:null
story is:null
area is:null
story is:10
area is:9760.8
C．前两个对象输出的结果是不定的，后一个对象的结果正确
D．前两个对象没有初值，因此程序编译时出错
