用到placement new这个叫做定位new,用这个new是不分配内存

#include <stdio.h>
#include <string.h>
#include <malloc.h>
//#include <new>

struct CLS
{
	int m_i;
	CLS( int i ):m_i(i) {}
	CLS()
	{
		new (this) CLS(0);//如果用到placement new这个叫做定位new,用这个new是不分配内存的
	}
	~CLS()
	{
		printf("destory!\n");
	}
};



int main(int argc, char* argv[])
{
	CLS  * c1=new CLS[3];
	
	printf("%d\n",c1[0].m_i);
	delete [] c1;
	return 0;
}