C++ 智能指针shared_ptr通过引用计数来管理指向的对象，不需要人工释放
这篇博文主要是讲解了智能指针的实现原理，怎么实现引用计数
#include <iostream> using namespace std; namespace shao_smart_point{ //智能指针内部引用计数类实现 class smart_cout{ private: int use_count; public: smart_cout():use_count(0){ } smart_cout(int count):use_count(count){ } int addRef(){ ++use_count; return use_count; } int releaseRef(){ --use_count; return use_count; } int getCount(){ return use_count; } }; //智能指针实现原理 template<class T> class smart_point{ private: T* pref; smart_cout* smartCount; public: //构造函数 smart_point():pref(nullptr),smartCount(nullptr){ } //构造函数 smart_point(T*data):pref(data),smartCount(new smart_cout()){ if(data != nullptr && smartCount != nullptr){ smartCount->addRef(); } } //拷贝构造 smart_point(const smart_point<T>& smartPoint){ //进行浅拷贝 this->pref = smartPoint.pref; this->smartCount = smartPoint.smartCount; //引用加1 if(this->smartCount != nullptr){ this->smartCount->addRef(); } } //赋值重载实现 void operator=(const smart_point<T>& smartPoint){ //清理自己之前的指向 if(this->pref != nullptr && this->smartCount->releaseRef() <= 0){ delete this->pref; delete this->smartCount; this->pref = nullptr; } //浅拷贝 this->pref = smartPoint.pref; this->smartCount = smartPoint.smartCount; this->smartCount->addRef(); } //重新指向 void reset(T * data){ if(this->pref != nullptr && this->smartCount->releaseRef() <= 0){ delete this->pref; delete this->smartCount; this->pref = nullptr; } this->pref = data; if(this->pref != nullptr){ this->smartCount = new smart_cout(1); }else{ this->smartCount = nullptr; } } void reset(const smart_point<T>& smartPoint){ if(this->pref != nullptr && this->smartCount->releaseRef() <= 0){ delete this->pref; delete this->smartCount; this->pref = nullptr; } this->pref = smartPoint.pref; this->smartCount = smartPoint.smartCount; if(this->pref != nullptr){ this->smartCount->addRef(); } } bool operator ==(const smart_point<T>& smartPoint){ return this->pref == smartPoint.pref; } T& operator*(){ return *pref; } T* get(){ return pref; } int useCount(){ if(smartCount != nullptr){ return smartCount->getCount(); } } //析构函数 ~smart_point(){ if(pref != nullptr && smartCount->releaseRef() <= 0){ //释放指针 delete pref; delete smartCount; pref = nullptr; cout << "delete" << endl; } } }; } void test(){ shao_smart_point::smart_point<int> mSmart(new int); shao_smart_point::smart_point<int> mSmart2(mSmart); mSmart2.reset(new int); cout << mSmart.useCount() << endl; cout << mSmart2.useCount() << endl; } void main(){ test(); cin.get(); }