#include <iostream>#include <memory>#include <Windows.h>#include <queue>#include <Psapi.h>using namespace std;static size_t	s_my_int_count = 0;const  int		MAX_LOOP_ = 3000000;const int      NORMAL_FLAG = 0x12ff0101;const int	   MY_INT_FLAG = 0x12ff0102;void* operator new(std::size_t size)throw(std::bad_alloc)//重写new操作符为的是统计我们关心的内存分配{	int addLen = sizeof(size_t);	void * p = std::malloc(addLen + 4 + size) ;	if (!p)		throw std::bad_alloc() ;	memcpy(p, &size, addLen);//标志实际长度	memcpy((char*)p + addLen, &NORMAL_FLAG, 4);//标志类型，普通---0x12ff0101, 我自己的int---0x12ff0102, 我自己的char[]---0x12ff0103	return ((char*)p + addLen + 4);}void* operator new(std::size_t size, int flag)throw(std::bad_alloc)// 对应于调用 “new(MY_INT_FLAG) int” 这样所有我们关心的内存多可以被监视{	int addLen = sizeof(size_t);	void * p = std::malloc(addLen + 4 + size) ;	if (!p)		throw std::bad_alloc() ;	if (flag == MY_INT_FLAG){		s_my_int_count ++;//统计关心的内存申请次数	}	memcpy(p, &size, addLen);//标志实际长度	memcpy((char*)p + addLen, &flag, 4);//放置标志位，标志类型，普通---0x12ff0101, 我自己的int---0x12ff0102, 我自己的char[]---0x12ff0103	return ((char*)p + addLen + 4);}void operator delete(void * q) throw(){	void* p;	int addLen = sizeof(size_t);	p = (char*)q - addLen - 4;//还原原来的指针位置，p是真正的系统malloc出来的指针	int flag;	memcpy(&flag, (char*)p + addLen, 4);//得到标志位		if (flag == MY_INT_FLAG){//统计关心的内存释放次数		s_my_int_count --;	}	if (p)		std::free(p) ;}void main(){	queue<int*>  intQueue;	int count = 0;	count = 0;	cout << "before push " << s_my_int_count << " int allocated"<< endl;	LONGLONG start = GetTickCount();	for (int i = 0; i < MAX_LOOP_; i ++)	{		int* p = new(MY_INT_FLAG) int;		intQueue.push(p);			}	cout << "after push " << s_my_int_count << " int allocated"<< endl;	while (!intQueue.empty()){		int* p = intQueue.front();		intQueue.pop();		delete p;//注意需要手动释放		count ++;	}	cout << "after pop " << s_my_int_count << " int allocated"<< endl;	cout << "===================raw int ptr for " << count << "/t" << GetTickCount() - start << endl;	unique_ptr<int> q(new int);	unique_ptr<int> r = move(q);// 编译正确，r（q） 和 r = q则编译失败，因为unique_ptr已经不允许使用“拷贝构造函数”	queue<unique_ptr<int>> intUniQueue;//因为unique_ptr没有“拷贝构造函数”  copy-constructor	//所以push（）的参数不能是“左值”，左值会调用“拷贝构造函数”	//只能是“右值”,右值则会调用“移动构造函数” move-constructor，  	//std::move()函数可以强制将左值转化成为右值	count = 0;	start = GetTickCount();		cout << "before push " << s_my_int_count << " int allocated"<< endl;	for (int i = 0; i < MAX_LOOP_; i ++)	{		unique_ptr<int> p(new(MY_INT_FLAG) int);		intUniQueue.push(std::move(p));//因为p不是“右值”，所以我们需要“显式”的调用move将p强制转为右值。	}	cout << "after push " << s_my_int_count << " int allocated"<< endl;	while (!intUniQueue.empty()){		unique_ptr<int> p = std::move(intUniQueue.front());//queue.front() 是一个左值引用，即queue.front()=2 合法。		intUniQueue.pop();		count ++;	}	cout << "after pop " << s_my_int_count << " int allocated"<< endl;	cout << "===================int unique  ptr for " << count << "/t" << GetTickCount() - start << endl;	queue<shared_ptr<int>> intSharedQueue;	count = 0;	start = GetTickCount();		cout << "before push " << s_my_int_count << " int allocated"<< endl;	for (int i = 0; i < MAX_LOOP_; i ++)	{		shared_ptr<int> p(new(MY_INT_FLAG) int);		intSharedQueue.push(p);	}	cout << "after push " << s_my_int_count << " int allocated"<< endl;	while (!intSharedQueue.empty()){		auto p = intSharedQueue.front();		intSharedQueue.pop();				count ++;	}	cout << "after pop " << s_my_int_count << " int allocated"<< endl;	cout << "===================int shared ptr for " << count << "/t" << GetTickCount() - start << endl;}/*智能指针省去了我们释放指针的精力，但是也需要一定的开销。unique_ptr 的开销相对于shared_ptr要小很多。如果一个资源每个时刻都只要有一个支配者，我们还是优先使用unique_ptr吧，效率会高很多。before push 0 int allocatedafter push 3000000 int allocatedafter pop 0 int allocated===================raw int ptr for 3000000      5375before push 0 int allocatedafter push 3000000 int allocatedafter pop 0 int allocated===================int unique  ptr for 3000000  7313before push 0 int allocatedafter push 3000000 int allocatedafter pop 0 int allocated===================int shared ptr for 3000000   11171请按任意键继续. . .*/