【c++】简单模拟实现boost库下的shared-ptr

//简单模拟实现boost库下的shared_ptr

#include <iostream>
#include <string.h>
using namespace std;

class shared_ptr_Rep
{
	friend class shared_ptr;
public:
	shared_ptr_Rep(const char *str = " ") :count(0)
	{
		px = new char[strlen(str) + 1];
		strcpy(px, str);
	}
	~shared_ptr_Rep()
	{
		delete[]px;
	}
public:
	void increment()
	{
		count++;
	}
	void decrement()
	{
		if (--count == 0)
		{
			delete this;// 哪一个rep的count为0了释放当时的rep
		}
	}
	char* get()
	{
		return px;
	}
private:
	char *px;
	int count;
};
//////////////////////////////////////////////////////////////////////

class shared_ptr
{
public:
	shared_ptr(const char *str = " ") :rep(new shared_ptr_Rep(str))
	{
		rep->increment();
	}
	shared_ptr(const shared_ptr &s) :rep(s.rep)
	{
		rep->increment();
	}
	shared_ptr& operator=(const shared_ptr &s)
	{
		if (this != &s)
		{
			rep->decrement();    // 迭代器
			rep = s.rep;
			rep->increment();
		}
		return *this;
	}
	~shared_ptr()
	{
		rep->decrement();
	}
public:
	char& operator*()
	{
		return *(rep->px);
	}
	char* operator->()
	{
		return rep->px;
	}
private:
	shared_ptr_Rep *rep;
};

int main()
{
	char *p = new char('a');
	char *q = new char('b');
	shared_ptr s1(p);
	cout << *s1 << endl;
	shared_ptr s2 = s1;
	cout << *s2 << endl;
	shared_ptr s3(q);
	s3 = s2;
	cout << *s3 << endl;
	shared_ptr s4(q);
	cout << *s4 << endl;
	shared_ptr s5 = s4;
	cout << *s5 << endl;
	return 0;
}

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