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:1 131 242 22 1