我在c#中定义了一些整形数a,b,c，其中c=a-b，pointf[] p=new pointf[9];我要把这个里面的9换成c，老出错，应该怎么改？

提示不能把非静态的变量用在数组里

            int k1, j1, nn;
            int i1=0;
            while (p_draw2[i1 + 1].Y - p_draw2[i1].Y < 2)
            {
                i1 = i1 + 1;
            }
            k1 = i1;
            int j = 8;
            while (p_draw2[j].Y - p_draw2[j - 1].Y < 2)
            {
                j = j - 1;
            }
            j1 = j;
            nn = j1 - k1;
            PointF[] p = new PointF[nn];
这样老出错

int nn;
        private  void xuanqu()
        {
            int k1, j1;
            int i1 = 0;
            while (p_draw2[i1 + 1].Y - p_draw2[i1].Y < 2)
            {
                i1 = i1 + 1;
            }
            k1 = i1;
            int j = 8;
            while (p_draw2[j].Y - p_draw2[j - 1].Y < 2)
            {
                j = j - 1;
            }
            j1 = j;
            nn = j1 - k1;
        }
PointF[] p = new PointF[nn];
这样还是出错

int nn;
        private  void xuanqu()
        {
            int k1, j1;
            int i1 = 0;
            while (p_draw2[i1 + 1].Y - p_draw2[i1].Y < 2)
            {
                i1 = i1 + 1;
            }
            k1 = i1;
            int j = 8;
            while (p_draw2[j].Y - p_draw2[j - 1].Y < 2)
            {
                j = j - 1;
            }
            j1 = j;
            nn = j1 - k1;
        }
 PointF[] p = new PointF[nn];

我这还是有错误，能不能帮我看一下

哦，谢谢！