没有ID的验证码图片，调用方法将图片保存到本地

首先须要添加mshtml的引用,之后using mshtml;

pictureBox1.Image = GetRegCodePic(webBrowser1, "", "code.en.img.php", "");  //第2－4个参数自己填
  //第2个参数为网页中图片的name(可能或ID也好用).
  //第3个参数为网页中图片的Src.
  //第2个参数为网页中图片的Alt.
  ////例<IMG height=80 alt="Registration Verification Code" src="......" width=290 border=0>
  pictureBox1.Image.Save("L:\\test\\111.bmp", pictureBox1.Image.RawFormat); //保存图片到本地

 public static Image GetRegCodePic(WebBrowser wbMail, string ImgName, string Src, string Alt)
        {
            HTMLDocument doc = (HTMLDocument)wbMail.Document.DomDocument;
            HTMLBody body = (HTMLBody)doc.body;
            IHTMLControlRange rang = (IHTMLControlRange)body.createControlRange();
            IHTMLControlElement Img;
            if (ImgName == "") //如果没有图片的名字,通过Src或Alt中的关键字来取
            {
                int ImgNum = GetPicIndex(wbMail, Src, Alt);
                if (ImgNum == -1) return null;
                Img = (IHTMLControlElement)wbMail.Document.Images[ImgNum].DomElement;
            }
            else
                Img = (IHTMLControlElement)wbMail.Document.All[ImgName].DomElement;

            rang.add(Img);
            rang.execCommand("Copy", false, null);
            Image RegImg = Clipboard.GetImage();
            Clipboard.Clear();
            return RegImg;

      

        

        }

        public static int GetPicIndex(WebBrowser wbMail, string Src, string Alt)
        {
            int imgnum = -1;
            for (int i = 0; i < wbMail.Document.Images.Count; i++)　//获取所有的Image元素
            {
                IHTMLImgElement img = (IHTMLImgElement)wbMail.Document.Images[i].DomElement;
                if (Alt == "")
                {
                    if (img.src.Contains(Src)) return i;
                }
                else
                {
                    if (!string.IsNullOrEmpty(img.alt))
                    {
                        if (img.alt.Contains(Alt)) return i;
                    }
                }
            }
            return imgnum;
        }