C#验证身份证的函数

这段c#代码主要是验证身份证的开头和身份证的格式和长度是否正确，没有按照身份证的编码规则进行严格验证

/// <summary>
    /// 验证身份证是否合法
    /// </summary>
    /// <param name="idcard">要验证的身份证</param>    
    public static bool isidcard(string idcard)
    {
      //如果为空，认为验证合格
      if (isnullorempty(idcard))
      {
        return true;
      }
 
      //清除要验证字符串中的空格
      idcard = idcard.trim();
 
      //模式字符串
      stringbuilder pattern = new stringbuilder();
      pattern.append(@"^(11|12|13|14|15|21|22|23|31|32|33|34|35|36|37|41|42|43|44|45|46|");
      pattern.append(@"50|51|52|53|54|61|62|63|64|65|71|81|82|91)");
      pattern.append(@"(\d{13}|\d{15}[\dx])$");
 
      //验证
      return regexhelper.ismatch(idcard, pattern.tostring());
    }

更为复杂些的验证方法：

private string checkcidinfo(string cid)
 {
  string[] acity = new string[]{null,null,null,null,null,null,null,null,null,null,null,"北京","天津","河北","山西","内蒙古",null,null,null,null,null,"辽宁","吉林","黑龙江",null,null,null,null,null,null,null,"上海","江苏","浙江","安微","福建","江西","山东",null,null,null,"河南","湖北","湖南","广东","广西","海南",null,null,null,"重庆","四川","贵州","云南","*",null,null,null,null,null,null,"陕西","甘肃","青海","宁夏","*",null,null,null,null,null,"*",null,null,null,null,null,null,null,null,null,"香港","澳门",null,null,null,null,null,null,null,null,"国外"};
  double isum=0;
  string info="";
  system.text.regularexpressions.regex rg = new system.text.regularexpressions.regex(@"^\d{17}(\d|x)$");
  system.text.regularexpressions.match mc = rg.match(cid);
  if(!mc.success)
  {
  return "";
  }  
  cid = cid.tolower();
  cid = cid.replace("x","a");
  if(acity[int.parse(cid.substring(0,2))]==null)
  {
  return "非法地区";
  }
  try
  {
  datetime.parse(cid.substring(6,4)+"-"+cid.substring(10,2)+"-"+cid.substring(12,2));
  }
  catch
  {
  return "非法生日";
  }
  for(int i=17;i>=0;i--)
  {  
  isum +=(system.math.pow(2,i)%11)*int.parse(cid[17-i].tostring(),system.globalization.numberstyles.hexnumber);

  }
  if(isum%11!=1)
  return("非法证号");
  
  return(acity[int.parse(cid.substring(0,2))]+","+cid.substring(6,4)+"-"+cid.substring(10,2)+"-"+cid.substring(12,2)+","+(int.parse(cid.substring(16,1))%2==1¡"男":"女"));
 
 }

调用测试：
response.write(checkcidinfo("340524198002300019"));
response.write(checkcidinfo("34052419800101001x"));

方法三：

/// <summary>
/// 身份证验证
/// </summary>
/// <param name="id">身份证号</param>
/// <returns></returns>
public bool checkidcard(string id)
{
  if (id.length == 18)
  {
     bool check = checkidcard18(id);
     return check;
   }
   else if (id.length == 15)
   {
     bool check = checkidcard15(id);
     return check;
   }
   else
   {
     return false;
   }
 }
 /// <summary>
 /// 18位身份证验证
 /// </summary>
 /// <param name="id">身份证号</param>
 /// <returns></returns>
 private bool checkidcard18(string id)
 {
   long n = 0;
   if (long.tryparse(id.remove(17), out n) == false || n < math.pow(10, 16) || long.tryparse(id.replace('x', '0').replace('x', '0'), out n) == false)
   {
     return false;//数字验证
   }
   string address = "11x22x35x44x53x12x23x36x45x54x13x31x37x46x61x14x32x41x50x62x15x33x42x51x63x21x34x43x52x64x65x71x81x82x91";
   if (address.indexof(id.remove(2)) == -1)
   {
     return false;//省份验证
   }
   string birth = id.substring(6, 8).insert(6, "-").insert(4, "-");
   datetime time = new datetime();
   if (datetime.tryparse(birth, out time) == false)
   {
     return false;//生日验证
   }
   string[] arrvarifycode = ("1,0,x,9,8,7,6,5,4,3,2").split(',');
   string[] wi = ("7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2").split(',');
   char[] ai = id.remove(17).tochararray();
   int sum = 0;
   for (int i = 0; i < 17; i++)
   {
     sum += int.parse(wi[i]) * int.parse(ai[i].tostring());
   }
   int y = -1;
   math.divrem(sum, 11, out y);
   if (arrvarifycode[y] != id.substring(17, 1).tolower())
   {
     return false;//校验码验证
   }
   return true;//符合gb11643-1999标准
 }
 /// <summary>
 /// 15位身份证验证
 /// </summary>
 /// <param name="id">身份证号</param>
 /// <returns></returns>
 private bool checkidcard15(string id)
 {
   long n = 0;
   if (long.tryparse(id, out n) == false || n < math.pow(10, 14))
   {
     return false;//数字验证
   }
   string address = "11x22x35x44x53x12x23x36x45x54x13x31x37x46x61x14x32x41x50x62x15x33x42x51x63x21x34x43x52x64x65x71x81x82x91";
   if (address.indexof(id.remove(2)) == -1)
   {
     return false;//省份验证
   }
   string birth = id.substring(6, 6).insert(4, "-").insert(2, "-");
   datetime time = new datetime();
   if (datetime.tryparse(birth, out time) == false)
   {
     return false;//生日验证
   }
   return true;//符合15位身份证标准
 }

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