下列程序的运行结果为______。
#include＜iostream. h＞
void print(double a)
{
cout＜＜++a;
}
void print(int a, int b)
{
cout＜＜b＜＜a;
}
void main()
{
print(1. 2);
cout＜＜" ";
print(3, 4);
}

单项选择题下列代码段中声明了3个类：class Person {};class Student: public Person {};class Undergraduate: Student {};下列关于这些类之间关系的描述中，错误的是______。

单项选择题有如下程序：#include＜iostream＞using namespace std;class Base{public:Base(int x=0):valB(x){cout＜＜valB;}～Base(){cout＜＜valB;}private:int valB;};class Derived:public Base{public:Derived(int x=0,int y=0):Base(x),valD(y){cout＜＜valD;}～Derived(){cout＜＜valD;}private:int valD;};int main(){Derived obj12(2,3);return 0;}运行时的输出结果是______。