C# 和 AForge - 使用未分配的局部变量 edgePoints

Question

我正在尝试编译这段代码（最后一个）： http://www.aforgenet.com/framework/features/blobs_processing.html

但它抛出：使用未分配的局部变量'edgePoints' ..

代码如下：

        BlobCounter blobCounter = new BlobCounter();
        blobCounter.ProcessImage(image23);
        Blob[] blobs = blobCounter.GetObjectsInformation();
        GrahamConvexHull hullFinder = new GrahamConvexHull();
        BitmapData data = image23.LockBits(new Rectangle(0, 0, image23.Width, image23.Height), ImageLockMode.ReadWrite, image23.PixelFormat);
        foreach (Blob blob in blobs)
        {
            List<IntPoint> leftPoints, rightPoints, edgePoints;
            blobCounter.GetBlobsLeftAndRightEdges(blob, out leftPoints, out rightPoints);
            edgePoints.AddRange(leftPoints);
            edgePoints.AddRange(rightPoints);
            List<IntPoint> hull = hullFinder.FindHull(edgePoints);
            Drawing.Polygon(data, hull, Color.Red);
        }
        image23.UnlockBits(data);

这是他有问题的行：

            edgePoints.AddRange(leftPoints);

我绑定了将 Null 分配给 edgePoints 但它失败了：

List<IntPoint> leftPoints, rightPoints, edgePoints= null;

有什么问题？我没有修改源代码，所以一切都应该正常..

Answer 1

你需要给它赋值：

List<IntPoint> leftPoints, rightPoints, edgePoints;
edgePoints = new List<IntPoint>();

在调用该实例的方法之前。

您的 leftPoints 和 rightPoints 可能由

初始化

blobCounter.GetBlobsLeftAndRightEdges(blob, out leftPoints, out rightPoints);

调用（注意 out 关键字），但 edgePoints 不是 - 你需要自己做。