/**   *    身份证   *   *    @param    string    $id   *    @return   boolean   */  function is_idcard( $id )  {      $id = strtoupper($id);      $regx = "/(^\d{15}$)|(^\d{17}([0-9]|X)$)/";      $arr_split = array();      if(!preg_match($regx, $id))      {          return FALSE;      }      if(15==strlen($id)) //检查15位      {          $regx = "/^(\d{6})+(\d{2})+(\d{2})+(\d{2})+(\d{3})$/";              @preg_match($regx, $id, $arr_split);          //检查生日日期是否正确          $dtm_birth = "19".$arr_split[2] . '/' . $arr_split[3]. '/' .$arr_split[4];          if(!strtotime($dtm_birth))          {              return FALSE;          } else {              return TRUE;          }      }      else           //检查18位      {          $regx = "/^(\d{6})+(\d{4})+(\d{2})+(\d{2})+(\d{3})([0-9]|X)$/";          @preg_match($regx, $id, $arr_split);          $dtm_birth = $arr_split[2] . '/' . $arr_split[3]. '/' .$arr_split[4];          if(!strtotime($dtm_birth))  //检查生日日期是否正确          {              return FALSE;          }          else          {              //检验18位身份证的校验码是否正确。              //校验位按照ISO 7064:1983.MOD 11-2的规定生成，X可以认为是数字10。              $arr_int = array(7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2);              $arr_ch = array('1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2');              $sign = 0;              for ( $i = 0; $i < 17; $i++ )              {                  $b = (int) $id{$i};                  $w = $arr_int[$i];                  $sign += $b * $w;              }              $n  = $sign % 11;              $val_num = $arr_ch[$n];              if ($val_num != substr($id,17, 1))              {                  return FALSE;              }              else              {                  return TRUE;              }          }      }      }