A function that verifies that the ID card is valid in PHP

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))//Check 15-bit {$regx = "/^ (\d{6}) + (\d{2}) + (\d{2}) + (\d{2}) + (\d{3}) $/";        @preg_match ($REGX, $id, $arr _split); Check that the birthday date is correct $dtm _birth = "+". $arr _split[2]. '/' . $arr _split[3].        '/'. $arr _split[4];        if (!strtotime ($dtm _birth)) {return FALSE;        } else {return TRUE; }} else//check 18-bit {$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))//Check whether the birthday date is correct {return FALSE;            } else {//verify that the check code for the 18-bit ID is correct.            The check digit is generated according to ISO 7064:1983.mod 11-2, and X can be considered the number 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 < $i + +) {$b = (int) $id {$i};                $w = $arr _int[$i];            $sign + = $b * $W;            } $n = $sign% 11;            $val _num = $arr _ch[$n];            if ($val _num! = substr ($id, 1)) {return FALSE;            } else {return TRUE; }        }    }}