I wrote several functions related to ID cards. I personally think they are quite useful. Especially when conducting online questionnaires, it is very useful to verify the ID cards in personal information. However, there are only a few applicants, so I might as well keep them in my blog. .
<?php
// Calculate ID card verification code according to national standard GB 11643-1999
function idcard_verify_number($idcard_base){
if (strlen($idcard_base) != 17){ return false; }
// Weighting factor
$factor = array(7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2);
//Corresponding value of check code
$verify_number_list = array('1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2');
$checksum = 0;
for ($i = 0; $i < strlen($idcard_base); $i++){
$checksum += substr($idcard_base, $i, 1) * $factor[$i];
}
$mod = $checksum % 11;
$verify_number = $verify_number_list[$mod];
return $verify_number;
}
// Upgrade the 15-digit ID card to 18-digit
function idcard_15to18($idcard){
if (strlen($idcard) != 15){
return false;
}else{
// If the ID card sequence code is 996 997 998 999, these are special codes for people over 100 years old
if (array_search(substr($idcard, 12, 3), array('996', '997', '998', '999')) !== false){
$idcard = substr($idcard, 0, 6) . '18'. substr($idcard, 6, 9);
}else{
$idcard = substr($idcard, 0, 6) . '19'. substr($idcard, 6, 9);
}
}
$idcard = $idcard . idcard_verify_number($idcard);
return $idcard;
}
// 18-digit ID card verification code validity check
function idcard_checksum18($idcard){
if (strlen($idcard) != 18){ return false; }
$idcard_base = substr($idcard, 0, 17);
if (idcard_verify_number($idcard_base) != strtoupper(substr($idcard, 17, 1))){
return false;
}else{
return true;
}
}
?>
The $idcard_base refers to the base code in the ID card. The base code is only found in the 18-digit ID card, which is the first 17 digits of the 18-digit ID card. The last digit is called the check code and is generally used. There is no need to call idcard_verify_number() directly. Most of the usual applications use the latter two functions. These functions do not care about the format of the ID string and perform the format check before calling.