全局类

#include <iostream>
using namespace std;
class A {
public:
    A(num):m_num(num) {cout << 1 << " " << m_num << endl;}
    ~A() {cout << 2 << " " << m_num << endl;}
private:
    int m_num;
};

A a(1);

int main () {
    cout << 3 << endl;
    A b(2);
    cout << 4 << endl;
    return 0;
}

结果:
1 1
3
1 2
4
2 2
2 1