c++ 智能指针shared_ptr实现

智能指针为一个带有指针和计数器的类

• 计数器使用指针实现，可以实现多个智能指针的计数器指向同一地址，方便计数

代码

#include "algorithm"
#include "iostream"
using namespace std;

template<typename T>
class shared_p{
private:
    unsigned int *count;
    T* ptr;
public:
    shared_p(T* p):ptr(p), count(new unsigned int(1)){}
    shared_p(const shared_p<T> &p):ptr(p.ptr), count(p.count){
        (*count)++;
    }
    shared_p(const T *p):ptr(p), count(new unsigned int(1)){}
    ~shared_p(){
        if(count != nullptr &&--(*count) == 0){
            delete count;
            delete ptr;
        }
    }
    unsigned int getCount(){
        return *(this->count);
    }
    shared_p<T>& operator= (const shared_p &p){
        if(this == &p)
            return *this;
        if(count != nullptr &&--(*count) == 0){
            delete count;
            delete ptr;
        }
        (*p.count)++;

        ptr = p.ptr;
        count = p.count;
        return *this;
    }

    T &operator*(){
        return *(this->ptr);
    }
    T *operator->(){
        return this->ptr;
    }
};

int main(){
    shared_p<string> p1(new string("hellow shared_ptr"));
    cout<<p1.getCount()<<endl;
    shared_p<string> p2(p1);
    cout<<p1.getCount()<<" "<<p2.getCount()<<endl;
    return 0;
}