PHP function to verify whether the ID card is legal

Is it legal, PHP

/**
 * ID card
 *
 * @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)) //Check 15 digits
 {
 $regx = "/^(d{6})+(d{2})+(d{2})+(d{2})+( d{3})$/";

 @preg_match($regx, $id, $arr_split);
 //Check whether the birthday date is correct
 $dtm_birth = "19".$arr_split[2] . '/' . $arr_split[3]. '/' .$arr_split[4];
 if(!strtotime($dtm_birth))
 {
 return FALSE;
 } else {
 return TRUE;
 }
 }
 else //Check 18 Bit
 {
 $regx = "/^(d{6})+(d{4})+(d{2})+(d{2})+(d{3})([0-9] | ;
 if(!strtotime($dtm_birth)) //Check whether the birthday date is correct
 {
 return FALSE;
 }
 else
 {
 //Check whether the check code of the 18-digit ID card is correct.
 //The check digit is generated in accordance with ISO 7064:1983.MOD 11-2. X can be considered as 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 < 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;
 }
 }
 }

}