本文介绍了一种C++智能指针的具体实现方式，通过自定义模板类`smart_ptr`来实现引用计数管理，避免内存泄漏。文章提供的实现包括了构造函数、析构函数、赋值操作符重载等关键部分。
希望对新手理解c++中智能指针的实现原理有所帮助，第一次上传代码，望各路道友多多指教。
#ifndef SMART_PTR_H
#define SMART_PTR_H
#include <map>
#include <iostream>
template <typename _Tr>
class smart_ptr
{
public:
typedef _Tr* pointType;
// 利用现有地址构造
smart_ptr(_Tr *ptr)
{
Increase((long)ptr);
this->ptr_ = ptr;
}
smart_ptr(const smart_ptr &other)
{
if(other.ptr_)
{
Increase((long)other.ptr_);
this->ptr_ = other.ptr_;
}
}
// 空初始化
smart_ptr()
{
this->ptr_ = NULL;
}
// 释放
~smart_ptr()
{
ReleasePtr();
}
public:
// 拷贝（递减原有计数、增加新计数）
smart_ptr &operator = (const smart_ptr &other)
{
this->ReleasePtr();
if(other.ptr_)
{
Increase((long)other.ptr_);
this->ptr_ = other.ptr_;
}
return *this;
}
// 解引
_Tr operator *()
{
//assert(this->ptr_);
return *this->ptr_;
}
// 模拟指针调用
pointType operator ->()
{
return this->ptr_;
}
private:
// 递增计数，并且返回计数
int Increase(long address)
{
int count = 0;
if(addressContainer_.find(address) != addressContainer_.end())
{
count = ++addressContainer_[address];
}
else
{
addressContainer_[address] = 1;
count = 1;
}
#ifdef PTR_DEBUG
std::cout << "address:" << address << " count:" << count << std::endl;
#endif
return count;
}
// 递减计数，并且返回计数
int Degression(long address)
{
int count = 0;
if(addressContainer_.find(address) != addressContainer_.end())
{
count = --addressContainer_[address];
if(count <= 0)
{
addressContainer_.erase(address);
}
#ifdef PTR_DEBUG
std::cout << "address:" << address << " count:" << count << std::endl;
#endif
}
return count;
}
void ReleasePtr()
{
int count = 0;
if(this->ptr_)
{
count = Degression((long)this->ptr_);
// 引用计数递减至0
if(!count)
{
delete this->ptr_;
#ifdef PTR_DEBUG
std::cout << "The address:" << (long)this->ptr_ << " has been delete!" << std::endl;
#endif
this->ptr_ = NULL;
}
}
}
// 地址容器（key：地址、value：被引用次数）
static std::map<long, int> addressContainer_;
pointType ptr_;
};
template <typename _Tr>
std::map<long, int> smart_ptr<_Tr>::addressContainer_;
#endif // SMART_PTR_H
扫一扫
1819
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
