第五章
7.
//7.
#include<iostream>
#include<cstdio>
using namespace std;
class Cat
{
private:
string s;
static int numofCats;
public:
Cat(string i):s(i){numofCats++;}
//~Cat(){numofCats--;}//本来想让它析构的时候归零，但是 会造成循环过后总数为0，所以 先空在这。
static void getNumberOfCats()
{
cout << numofCats << endl;
}
};
int Cat::numofCats = 0;
int main()
{
string a;
while(cin >> a)
Cat d(a);
Cat::getNumberOfCats();
return 0;
}
14
#include<iostream>
#include<cstdio>
using namespace std;
class Car;
class Boat
{
private:
double weight;
public:
Boat(double j):weight(j){}
friend double getTotalWeight(Boat &a, Car &b);
};
class Car
{
private:
double weight;
public:
Car(double j):weight(j){}
friend double getTotalWeight(Boat &a, Car &b);
};
double getTotalWeight(Boat &a, Car &b)
{
return a.weight + b.weight;
}
int main()
{
double a, b;
cin >> a >> b;
Boat d(a);
Car c(b);
cout << getTotalWeight(d, c) << endl;
return 0;
}