object构造、拷贝构造、析构、临时对象

 

#include <iostream>
using namespace std;

class howmany
{
static int count;

public:
howmany()
{
count++;
}

static void print(const char *msg = 0)
{
if (msg) cout << msg << ": ";
cout << "count = " << count << endl;
}

~howmany()
{
count--;
cout <<  "~howmany: " << count << endl;
}

};

int howmany::count = 0;
howmany f(howmany x)
{
x.print("x arg inside f()");
return x;
}

int main()
{
howmany h;

howmany::print("after h");
howmany h2 = f(h);
howmany::print("after call f()");
}

 

输出：

after h: count = 1

x arg inside f(): count = 1

~howmany: 0

after call f(): count = 0

~howmany: -1

~howmany: -2