C#中如何利用正则表达式判断字符

废话不多说了，下面代码给大家介绍下利用正则表达式判断字符的方法，具体代码如下所示：

using system;
using system.text.regularexpressions;
using system.net;
namespace 正则表达式检测字符串
{
 class program
 {
  static void main(string[] args)
  {
   console.writeline("请输入字符串：");
   string s = console.readline();
   if (gf_isok.isexisthanzi(s))
   {
    console.write("包含汉字");
   }
   else
   {
    console.write("不包含汉字");
   }
   console.readline();
  }
 }
 //判断部分
 public class gf_isok
 {
  /// <summary>
  /// 判读是否是ip地址
  /// </summary>
  /// <param name="in_str"></param>
  /// <returns></returns>
  public static bool isipstr(string in_str)
  {
   ipaddress ip;
   return ipaddress.tryparse(in_str, out ip);
  }
  /// <summary>
  /// 判断是否是数字
  /// </summary>
  /// <param name="strnumber"></param>
  /// <returns></returns>
  public static bool isnumber(string strnumber)
  {
   regex objnotnumberpattern = new regex("[^0-9.-]");
   regex objtwodotpattern = new regex("[0-9]*[.][0-9]*[.][0-9]*");
   regex objtwominuspattern = new regex("[0-9]*[-][0-9]*[-][0-9]*");
   string strvalidrealpattern = "^([-]|[.]|[-.]|[0-9])[0-9]*[.]*[0-9]+$";
   string strvalidintegerpattern = "^([-]|[0-9])[0-9]*$";
   regex objnumberpattern = new regex("(" + strvalidrealpattern + ")|(" + strvalidintegerpattern + ")");
   return !objnotnumberpattern.ismatch(strnumber) &&
     !objtwodotpattern.ismatch(strnumber) &&
     !objtwominuspattern.ismatch(strnumber) &&
     objnumberpattern.ismatch(strnumber);
  }
  /// <summary>
  /// 判断是否是日期字符串
  /// </summary>
  /// <param name="in_str"></param>
  /// <returns></returns>
  public static bool isdatestr_yyyymmdd(string in_str)
  {
   if (in_str == "") return true;
   if (in_str.length != 8) return false;
   return isdatestr(in_str);
  }
  /// <summary>
  /// 判断是否是日期字符串
  /// </summary>
  /// <param name="in_str"></param>
  /// <returns></returns>
  public static bool isdatestr(string in_str)
  {
   if (in_str == "") return true;
   if (in_str.length == 8)
    in_str = in_str.substring(0, 4) + "-" + in_str.substring(4, 2) + "-" + in_str.substring(6, 2);
   datetime dtdate;
   bool bvalid = true;
   try
   {
    dtdate = datetime.parse(in_str);
   }
   catch (formatexception)
   {
    // 如果解析方法失败则表示不是日期性数据
    bvalid = false;
   }
   return bvalid;
  }
  /// <summary>
  /// 判断字符串中是否包含汉字,有返回true 否则为false
  /// </summary>
  /// <param name="str"></param>
  /// <returns></returns>
  public static bool isexisthanzi(string str)
  {
   regex reg = new regex(@"[\u4e00-\u9fa5]");//正则表达式
   if (reg.ismatch(str))
   {
    return true;
   }
   else
   {
    return false;
   }
  }

  /// <summary>
  /// 字段串是否为null或为""(空)
  /// </summary>
  /// <param name="str"></param>
  /// <returns></returns>
  public static bool isstrnullorempty(string str)
  {
   if (str == null || str.trim() == string.empty)
    return true;
   return false;
  }
  /// <summary>
  /// 返回文件是否存在
  /// </summary>
  /// <param name="filename">文件名</param>
  /// <returns>是否存在</returns>
  public static bool isfileexists(string filename)
  {
   return system.io.file.exists(filename);
  }

  /// <summary>
  /// 检测是否符合email格式
  /// </summary>
  /// <param name="stremail">要判断的email字符串</param>
  /// <returns>判断结果</returns>
  public static bool isvalidemail(string stremail)
  {
   return regex.ismatch(stremail, @"^[\w\.]+([-]\w+)*@[a-za-z0-9-_]+[\.][a-za-z0-9-_]");
  }
  public static bool isvaliddoemail(string stremail)
  {
   return regex.ismatch(stremail, @"^@((
[0−9]1,3\.[0−9]1,3\.[0−9]1,3\.)|(([\w−]+\.)+))([a−za−z]2,4|[0−9]1,3)(
?)$");
  }
  /// <summary>
  /// 检测是否是正确的url
  /// </summary>
  /// <param name="strurl">要验证的url</param>
  /// <returns>判断结果</returns>
  public static bool isurl(string strurl)
  {
   return regex.ismatch(strurl, @"^(http|https)\://([a-za-z0-9\.\-]+(\:[a-za-z0-9\.&%\$\-]+)*@)*((25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])|localhost|([a-za-z0-9\-]+\.)*[a-za-z0-9\-]+\.(com|edu|gov|int|mil|net|org|biz|arpa|info|name|pro|aero|coop|museum|[a-za-z]{1,10}))(\:[0-9]+)*(/($|[a-za-z0-9\.\,\?\'\\\+&%\$#\=~_\-]+))*$");
  }
 
  /// <summary>
  /// 判断是否为base64字符串
  /// </summary>
  /// <param name="str"></param>
  /// <returns></returns>
  public static bool isbase64string(string str)
  {
   //a-z, a-z, 0-9, +, /, =
   return regex.ismatch(str, @"[a-za-z0-9\+\/\=]");
  }
  /// <summary>
  /// 检测是否有sql危险字符
  /// </summary>
  /// <param name="str">要判断字符串</param>
  /// <returns>判断结果</returns>
  public static bool issafesqlstring(string str)
  {
   return !regex.ismatch(str, @"[-|;|,|\/|||
|
|\}|\{|%|@|\*|!|\']");
  }
 }
}

以上所述是小编给大家介绍的c#中如何利用正则表达式判断字符，希望对大家有所帮助