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C#正则函数用法实例【匹配、替换、提取】

1 正则表达式的常见使用

① 格式匹配

/// <summary>
/// 邮箱格式验证
/// </summary>
/// <returns></returns>
public static string CheckMail(string strEmail)
{
  string result = "";
  Regex regex = new Regex(@"[a-zA-Z0-9._%-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}");
  Match match = regex.Match(strEmail);
  if(match.Success)
  {
    result = strEmail;
  }
  else
  {
    result = "无效邮箱";
  }
  return result;
}

② 替换匹配内容

/// <summary>
/// 转换日期格式(yyyy-MM-dd 转 yyyy年MM月dd日)
/// </summary>
/// <param name="strDate"></param>
/// <returns></returns>
public static string TransDate(string strDate)
{
  string result = "";
  Regex regex = new Regex(@"(\d+)-(\d+)-(\d+)");
  if(regex.IsMatch(strDate))
  {
    result = regex.Replace(strDate,"$1年$2月$3日");
  }
  return result;
}

③ 提取匹配内容

/// <summary>
/// 正则表达式提取和替换内容
/// </summary>
public static string Contentextract()
{
  string result = "";
  string str = "大家好! <User EntryTime='2010-10-7' Email='zhangsan@163.com'>张三</User> 自我介绍。";
  Regex regex = new Regex(@"<User\s*EntryTime='(?<time>[\s\S]*?)'\s+Email='(?<email>[\s\S]*?)'>(?<userName>[\s\S]*?)</User>", RegexOptions.IgnoreCase);
  Match match = regex.Match(str);
  if(match.Success)
  {
    string userName = match.Groups["userName"].Value; //获取用户名
    string time = match.Groups["time"].Value; //获取入职时间
    string email = match.Groups["email"].Value; //获取邮箱地址
    string strFormat = String.Format("我是:{0},入职时间:{1},邮箱:{2}", userName, time, email);
    result = regex.Replace(str, strFormat); //替换内容
    Console.WriteLine(result);
  }
  return result;  //结果:大家好!我是张三,入职时间:2010-10-7,邮箱:zhangsan@163.com 自我介绍。
}