有以下程序#include ＜iostream＞using namespace std;static int days []={31,28.31,30,31,30,31,31,30,31,30,31};class date{private: int month, day, year:public: date (int m, int d, int y {month = m;day = d;year = y; } date{} {} void disp {) { cout ＜＜year＜＜" - "＜＜month＜＜ "- "＜＜day＜＜end1; } date operator+(int day) { date dt = *this: day += dt.day; while { day ＞ days[ dt.month - 1 ] ) { day -= tays[ dt.month - 1 ]; if ( ++dt.month == 13 { dt.month = 1; dt.yeare++; }} dr. day = day; return dt; }};int main(){ date d1( 6, 20, 2004 ), d2; d2.= d1 + 20; d2.disp (); return 0; } 执行后的输出结果是
A．2004-7-10
B．2004-6-20
C．2004-7-20
D．程序编译时出错
