delphi身份证验证

function ValidatePID(const APID: string): string;

  {内部函数,取身份证号校验位,最后一位,对18位有效}

  function GetVerifyBit(sIdentityNum: string): Char;

  var

    nNum: Integer;

  begin

    Result := #0;

    nNum := StrToInt(sIdentityNum[1]) * 7 +

            StrToInt(sIdentityNum[2]) * 9 +

            StrToInt(sIdentityNum[3]) * 10 + 

            StrToInt(sIdentityNum[4]) * 5 +

            StrToInt(sIdentityNum[5]) * 8 +

            StrToInt(sIdentityNum[6]) * 4 +

            StrToInt(sIdentityNum[7]) * 2 +

            StrToInt(sIdentityNum[8]) * 1 +

            StrToInt(sIdentityNum[9]) * 6 +

            StrToInt(sIdentityNum[10]) * 3 +

            StrToInt(sIdentityNum[11]) * 7 +

            StrToInt(sIdentityNum[12]) * 9 +

            StrToInt(sIdentityNum[13]) * 10 +

            StrToInt(sIdentityNum[14]) * 5 +

            StrToInt(sIdentityNum[15]) * 8 +

            StrToInt(sIdentityNum[16]) * 4 +

            StrToInt(sIdentityNum[17]) * 2;

    nNum := nNum mod 11;

    case nNum of

      0: Result := '1';

      1: Result := '0';

      2: Result := 'X';

      3: Result := '9';

      4: Result := '8';

      5: Result := '7';

      6: Result := '6';

      7: Result := '5';

      8: Result := '4';

      9: Result := '3';

      10: Result := '2';

    end;

  end;

var

  L : Integer;

  sCentury : string;

  sYear2Bit,sYear4Bit : string;

  sMonth : string;

  sDate : string;

  iCentury : Integer;

  iMonth : Integer;

  iDate : Integer;

  CRCFact : string;//18位证号的实际值

  CRCTh : string; //18位证号的理论值

  FebDayAmt: Byte;//2月天数

begin

  L := Length(APID);

  if (L in [15, 18]) = False then

  begin

     Result := Format('身份证号不是15位或18位(%0:s, 实际位数:%1:d)', [APID, L]);

     Exit;

  end;

  CRCFact := '';

  if L = 18 then

  begin

     sCentury := Copy(APID, 7, 2);

     iCentury := StrToInt(sCentury);

     if (iCentury in [18..20]) = False then

     begin

        Result := Format('身份证号码无效:18位证号的年份前两位必须在18-20之间(%0:S)', [sCentury]);

        Exit;

     end;

     sYear2Bit := Copy(APID, 9, 2);

     sYear4Bit := sCentury + sYear2Bit;

     sMonth := Copy(APID, 11, 2);

     sDate := Copy(APID, 13, 2);

     CRCFact := Copy(APID, 18, 1);

  end else

  begin

     sCentury := '19';

     sYear2Bit := Copy(APID, 7, 2);

     sYear4Bit := sCentury + sYear2Bit;

     sMonth := Copy(APID, 9, 2);

     sDate := Copy(APID, 11, 2);

  end;

  iMonth := StrToInt(sMonth);

  iDate := StrToInt(sDate);

  if (iMonth in [01..12]) = False then

  begin

     Result := Format('身份证号码无效:月份必须在01-12之间(%0:s)', [sMonth]);

     Exit;

  end;

  if (iMonth in [1, 3, 5, 7, 8, 10, 12]) then

  begin

     if (iDate in [01..31]) = False then

     begin

        Result := Format('身份证号码无效:日期无效,不能为零或超出当月最大值(%0:s)', [sDate]);

        Exit;

     end;

  end;

  if (iMonth in [4, 6, 9, 11]) then

  begin

     if (iDate in [01..30]) = False then

     begin

        Result := Format('身份证号码无效:日期无效,不能为零或超出当月最大值(%0:s)', [sDate]);

        Exit;

     end;

  end;

  if IsLeapYear(StrToInt(sCentury + sYear2Bit)) = True then

  begin

     FebDayAmt := 29;

  end else

  begin

     FebDayAmt := 28;

  end;

  if (iMonth in [2]) then

  begin

     if (iDate in [01..FebDayAmt]) = False then

     begin

        Result := Format('身份证号码无效:日期无效,不能为零或超出当月最大值(%0:s)', [sDate]);

        Exit;

     end;

  end;

  if CRCFact <> '' then

  begin

     CRCTh := GetVerifyBit(APID);

     if CRCFact <> CRCTh then

     begin

        Result := Format('身份证号码无效:校验位(第18位)错:(%0:s)', [APID]);

        Exit;

     end;

  end;

  Result :=  '1';

end;