结构体变量存放内存中，也有起始地址，定义一个变量来存放这个地址，那这个变量就是结构体指针；

typedef struct mydata{
	int a1;
	int a2;
	int a3;
}mydata;

void CJgtzzView::OnDraw(CDC* pDC)
{
	CJgtzzDoc* pDoc = GetDocument();
	ASSERT_VALID(pDoc);
	// TODO: add draw code for native data here
	CString str1;

	mydata b;
    b.a1=101;b.a2=202;b.a3=303;
    mydata * a = &b;

	str1.Format("%d", a->a1);pDC->TextOut(50, 50, str1);
	str1.Format("%d", a->a2);pDC->TextOut(100, 50, str1);
	str1.Format("%d", a->a3);pDC->TextOut(150, 50, str1);
	
    int *c = (int*)&b;
	str1.Format("%d", *c);pDC->TextOut(50, 80, str1);
	str1.Format("%d", *(c+1));pDC->TextOut(100, 80, str1);
	str1.Format("%d", *(c+2));pDC->TextOut(150, 80, str1);
}

a是mydata类型的指针，a->a1、a->a2这样来访问成员；

后一种写法功能上是等价的；