C++ 定义一个引用计数的类

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本文详细介绍了C++中HasPtr类的实现，包括构造函数、拷贝构造函数、赋值运算符和析构函数。HasPtr类用于演示智能指针的概念，通过引用计数来管理动态分配的字符串资源。

#ifndef HASPTR_H
#define HASPTR_H
#include

class HasPtr
{
public:
HasPtr(const std::string &s =std::string()):
ps(new std::string(s)),i(0),use(new std::size_t(1)){};

    HasPtr(const HasPtr& p):
        ps(p.ps),i(p.i),use(p.use){++*use;}

    HasPtr& operator=(const HasPtr&);

    ~HasPtr();

private:
std::string *ps;
int i ;
std::size_t *use;

};

#endif // HASPTR_H

#include “hasptr.h”

HasPtr::~HasPtr()
{
if(–*use==0)
{
delete ps;
delete use;
}

}

HasPtr& HasPtr::operator=(const HasPtr &s)
{
++*s.use;

/// if the left one of = is a new HasPtr object,
/// the 'use' of it is 1,so delete its own memory
/// and add the right items to it; 
/// 
/// when it is resign itself again,the memory will
/// not be destoryed;
if(--*use ==0)
{
    delete ps;
    delete use;
}

ps = s.ps;
i = s.i;
use = s.use;
return *this;

}