关于二级指针

最新推荐文章于 2021-01-22 22:22:50 发布

原创最新推荐文章于 2021-01-22 22:22:50 发布 · 595 阅读

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#include #object #扩展 #c

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#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;
struct mst
{
	int *a;//对齐，扩展为8字节
	double f;
	int *b;
	int *c;
};
int main()
{
	mst st;
	int array1[2]= {1,2};
	int array2[3]= {3,4,5};
	int array3[2]= {6,7};
	st.a=array1;
	st.b=array2;
	st.c=array3;
	int **addr=(int**)&st;
	cout<<addr[0][1]<<endl;
	cout<<addr[4][0]<<endl;//4个整数偏移量。a对齐后8字节，f也是8字节，共16个字节，4个32位。
	cout<<addr[5][1]<<endl;
	/*cout<<"oa="<<offsetof( mst, a )<<endl; //0
	cout<<"of="<<offsetof(mst,f)<<endl; //8
	cout<<"ob="<<offsetof(mst,b)<<endl; //16
	cout<<"oc="<<offsetof(mst,c)<<endl; //20*/
	cout<<"size of object:"<<sizeof(mst)<<endl;
	system("pause");
	return 0;
}