c# 版 18位身份證嚴格驗證及 15位轉18位

private string GetCard(string cid)

        {

            if (cid.Length == 15)

            {

                cid = per15To18(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,"遼甯","吉林","黑龍江",null,null,null,null,null,null,null,"上海","江蘇","浙江","安微","福建","江西","山東",null,null,null,"河南","湖北","湖南","廣東","廣西","海南",null,null,null,"重慶","四川","貴州","雲南","西藏",null,null,null,null,null,null,"陝西","甘肅","青海","甯夏","***",null,null,null,null,null,"台灣",null,null,null,null,null,null,null,null,null,"香港","澳門",null,null,null,null,null,null,null,null,"國外"};

            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 "格式不正确!";

                return "";

            cid = cid.ToLower();

            cid = cid.Replace("x","a");

            if(aCity[int.Parse(cid.Substring(0,2))]==null)

                //return "非法地區";

            try

                 DateTime.Parse(cid.Substring(6,4)+"-"+cid.Substring(10,2)+"-"+cid.Substring(12,2));

            catch

                 //return "非法生日";

                 return "";

            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("非法證号");

                return("");

            return(cid.Substring(6,4)+"-"+cid.Substring(10,2)+"-"+cid.Substring(12,2));

        }

private string per15To18(string perIDSrc)

            int iS = 0;

            //權重因子常數

            int[] iW = new int[] { 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2 };

            //校驗碼常數

            string LastCode = "10X98765432";

            //新身份證号

            string perIDNew;

            perIDNew = perIDSrc.Substring(0, 6);

            //填在第6位及第7位上填上‘1’，‘9’兩個數字

            perIDNew += "19";

            perIDNew += perIDSrc.Substring(6, 9);

            //進行權重求和

            for (int i = 0; i < 17; i++)

                iS += int.Parse(perIDNew.Substring(i, 1)) * iW[i];

            //取模運算，得到模值

            int iY = iS % 11;

            //從LastCode中取得以模為索引号的值，加到身份證的最後一位，即為新身份證号。

            perIDNew += LastCode.Substring(iY, 1);

            return perIDNew;

轉載他處，位址不詳，以備不時之需。