获取图片地址代码（严格按HTML编写的图片地址）

protected string GetPic(string tempstr)
    {

        string str = tempstr.ToLower();
int stop;

        int start = str.IndexOf("src=\"");
        if (start > 0)
        {
            stop = str.IndexOf("\"", start);
        }
        else
        {

            stop = 0;

        }

        if (stop > 0)
        {

            string imgcode = str.Substring(start, stop - start);

            if (imgcode != null)
            {
                return imgcode;
            }
            else
            {
                return "nopic.gif";

            }

        }
        else
        {

            return "nopic.gif";
        }

    }