C++ Primer（第5版） 练习 13.27

练习 13.27 定义你自己的使用引用计数版本的HasPtr。

环境：Linux Ubuntu（云服务器）

工具：vim

代码块

class HasPtr{
    public:
    HasPtr(const string &s = string()): ps(new string(s)), i(0), use(new size_t(1)) {}
    HasPtr(const HasPtr &s): ps(s.ps), i(s.i), count(s.use) { ++*count; }
    HasPtr& operator= (const HasPtr &s);
    ~HasPtr();

    private:
    string *ps;
    int i;
    size_t *count;
};

HasPtr::~HasPtr(){
    if(--*count == 0){
        delete ps;
        delete count;
    }
}

HasPtr& HasPtr::operator= (const HasPtr &s){
    ++*s.count;
    if(--*count == 0){
        delete ps;
        delete count;
    }
    ps = s.ps;
    i = s.i;
    count = s.count;
    return *this;
}