下面程序的执行结果是（)。#include＜iostream＞using namespace std;class building {public:buildi

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