单项选择题有如下两个类定义:class XX {private:double x1;protected:double x2;public:double x3;};class YY: protected XX {private:double y1;protected:double y2;public:double y3;};在类YY中保护成员变量的个数是______。
单项选择题有如下程序:#include<iostream>using namespace std;class TV{public:TV(int s=41):size(s){}TV(const TV&r):size(r.size) {cout<< 1 ;}~TV(){}private:int size;};TV fun(TV &u){TV t=u; return t; }int main() {TV x, y; x=fun(y); return 0; }此程序运行时输出字符1的个数是______。