5月25日打卡

运行下面程序，观察输出结果

#include<iostream>
using namespace std;
int x = 5, y = 7;
void myFunction() {
    int y = 10;
    cout << "x from myFunction:" << x << "\n";
    cout << "y from myFunction: " << y << "\n\n";

}
int main()
{
    cout << "x from main:" << x << "\n";
    cout << "y from main:" << y << "\n\n";
    myFunction();
    cout << "Back from myFunction!\n\n";
    cout << "x from main:" << x << "\n";
    cout << "y from main:" << y << "\n";
    return 0;
}

题目描述：

定义一个Cat类，拥有静态数据成员numOFCats，记录Cat的个体数目，静态成员函数getNumOFCats（），读取numOFCats。设计程序测试这个类，体会静态数据成员和静态成员函数的用法。

#include<iostream>
using namespace std;
class Cat {
private:
    int a;
    static int numOFCats;
public:
    Cat(int a) :a(a) { numOFCats++; }
    static int getnumOFCats()
    {
        return numOFCats;
    }
    ~Cat() { numOFCats--; }
};
int Cat::numOFCats = 0;
int mian()
{
    int a;
    cin >> a;
    Cat x(a);
    cout << x.getnumOFCats() << endl;
}