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