object构造、拷贝构造、析构、临时对象

最新推荐文章于 2024-11-15 15:04:58 发布

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本文通过一个C++示例程序展示了如何使用静态成员变量来跟踪类实例的数量变化，并在构造和析构函数中更新计数。此外，还演示了静态成员函数的用法。

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#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