Ｃ＃正则表达式校验

 static void Main(string[] args)
        {
            WebClient wc = new WebClient();
            //要把网页以字符串的形式下载下来
            string htmlstr = wc.DownloadString("http://zhidao.baidu.com/link?url=6kcGgrcqb84u-4NDe7aoUSCdmHVt-2DbKffrD5DiwZodgalkfPbnbhD1Hy2v_By4k2IN6tYtFt59Qwor7HRLpHflaaHnoXGYR9dhGX1r55K");
            MatchCollection mc = Regex.Matches(htmlstr, "[0-9a-zA-Z_.-]+@[0-9a-zA-Z_.]+([.][a-zA-Z]+){1,2}");
            foreach (Match item in mc)
            {
                if (item.Success)//是否匹配成功，写上更好
                {
                    Console.WriteLine(item.Value);
                }
            }
            Console.ReadKey();

        }

        static void Main(string[] args)
        {
            string eamil = Console.ReadLine();
            //是否匹配
            bool result = Regex.IsMatch(eamil, "[0-9a-zA-Z_.-]+@[0-9a-zA-Z_.]+([.][a-zA-Z]+){1,2}");

            //获取匹配的结果
            Match mt = Regex.Match(eamil, "[0-9a-zA-Z_.-]+@[0-9a-zA-Z_.]+([.][a-zA-Z]+){1,2}");

            Console.WriteLine(result);
            Console.WriteLine(mt.Value);
            Console.ReadKey();


        }

获取网页的图片：

using System;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;

namespace GetPictures
{
    class Program
    {
        static void Main(string[] args)
        {
            //首先下载页面
            WebClient wc = new WebClient();
            wc.Encoding = Encoding.UTF8;
            string html = wc.DownloadString("https://www.camarts.cn/archives/3020.html");
            MatchCollection mc = Regex.Matches(html, "<img\sclass="aligncenter\ssize-full\swp-image-[0-9]{4}?"\ssrc="(.+?)".+?>");



            //遍历匹配的内容
            int i=0;
            foreach (Match item in mc)
            {
                i++;
                if (item.Success)
                {
                    string path = item.Groups[1].Value;//图片下载地址

                    //下载图片
                    if(i%2==0)
                    {
                    wc.DownloadFile(path, @"D:高清图片" + i + ".jpg");
                    Console.WriteLine("★"+i/2);//进度 
                    }
                    /*
                     <img class="aligncenter size-full wp-image-3021" src="https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9659.jpg?imageView/2/w/800/h/800/q/90" data-original="https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9659.jpg?imageView/2/w/800/h/800/q/90" alt="IMG_9659" width="800" height="533" srcset="https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9659.jpg 800w, https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9659-150x99.jpg 150w, https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9659-300x199.jpg 300w, https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9659-450x300.jpg 450w" sizes="(max- 800px) 100vw, 800px" style="display: block;">
                     <img class="aligncenter size-full wp-image-3022" src="https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9668.jpg?imageView/2/w/800/h/800/q/90" data-original="https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9668.jpg?imageView/2/w/800/h/800/q/90" alt="IMG_9668" width="800" height="533" srcset="https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9668.jpg 800w, https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9668-150x99.jpg 150w, https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9668-300x199.jpg 300w, https://dn-ssl-img-camarts.qbox.me/2014/07/IMG_9668-450x300.jpg 450w" sizes="(max- 800px) 100vw, 800px" style="display: block;">
                     <img\sclass="aligncenter\ssize-full\swp-image-[1-9]+"\ssrc="(.+.+?)".+?>                
                     */
                }
            }
            Console.ReadKey();
        }
    }
}