PHP regular expression to verify the accuracy of ID number

In the process of website development, it is often necessary to verify the data entered by the user, and the verification of the ID number involved is a very important part of it. The ID number is the only proof of personal identity, and it is crucial to verify the accuracy of the ID number. This article will introduce how to use PHP regular expressions to verify the accuracy of ID numbers.

Basic rules for ID number
The ID number is composed of 18 digits and letters (X), of which the first 17 digits are in a fixed format, and the last digit may be a number or "X" ". The first 6 digits of the ID number are the area code, the middle 8 digits are the date of birth, and the last 4 digits are a check code consisting of region, gender and sequence number. Among them, the area code, date of birth, and check code have fixed rules.

Verification of ID number

Using the preg_match function in PHP can easily verify the ID number. The first parameter of the preg_match function is the regular expression to be matched, and the second parameter is the string to be matched. The following is an example:

$pattern = '/^d{17}[Xd]$/';
$id = '110101199001011234'; //ID number to be verified
if (preg_match($pattern, $id)) {

//身份证号码格式正确

} else {

//身份证号码格式错误

}

In the above code, the regular expression $pattern is used to verify identity certificate number. It indicates that the ID number should consist of 17 digits and a number or letter "X". Next, we will explain in detail how the various parts of the ID number should match.

Matching area code

The first 6 digits of the ID number are the area code, indicating the administrative division where the ID number is located. Among them, the first two digits represent the province, and the last four digits represent the city or county. Area codes are uniformly assigned by the state, and each administrative division has a corresponding code.

We can use the following regular expression to match area codes:

$area_pattern = '/^([1-9]d|([1-9][0-9]) d{4})$/';
$area_code = substr($id, 0, 6); //Get the first 6 digits of the area code from the ID number
if (preg_match($area_pattern, $area_code )) {

//区域代码格式正确

} else {

//区域代码格式错误

}

In the above code, the regular expression $area_pattern is used to match the area code. It indicates that the area code should consist of 6 digits. $area_code is used to extract the first 6 digits of the area code from the ID number.

Match date of birth

The middle 8 digits of the ID number are the date of birth, indicating the year, month and day of the holder’s birth. Among them, the first 4 digits represent the year, the last 2 digits represent the month, and the last 2 digits represent the number of days. The date of birth should comply with certain rules, such as the year cannot exceed the current year, etc.

We can use the following regular expression to match the correct date of birth:

$birthday_pattern = '/^((19|20)d{2})(0[1-9] |1[012])(0[1-9]|[12][0-9]|3[01])$/';
$birthday = substr($id, 6, 8); // Get the middle 8-digit date of birth from the ID number
if (preg_match($birthday_pattern, $birthday)) {

//出生日期格式正确

} else {

//出生日期格式错误

}

In the above code, the regular expression $birthday_pattern is used to match the correct date of birth. It indicates that the date of birth should consist of 4 digits representing the year, 2 digits representing the month, and 2 digits representing the day. $birthday is used to extract the middle 8-digit date of birth from the ID number.

Matching verification code

The last digit of the ID number is the verification code, which is used to verify whether the ID number is correct. The check code is calculated from the first 17 digits, which consists of information such as region, gender, and sequence number. Through a certain algorithm, a check code can be obtained. If it is the same as the last digit of the ID number, it means that the ID number is correct.

We can use the following regular expression to match the check code:

$check_code_pattern = '/^d{17}[Xd]$/';
if (preg_match($ check_code_pattern, $id)) {

$n = 0;
for ($i = 0; $i < 17; $i++) {
    $n += $id[$i] * pow(2, 17 - $i) % 11;
}
$check_code = $n % 11 == 1 ? 'X' : (12 - $n % 11);
if ($check_code == substr($id, -1)) {
    //身份证号码校验通过
} else {
    //身份证号码校验失败
}

} else {

//身份证号码格式错误

}

In the above code, the regular expression $check_code_pattern is used to ensure that the ID number matches the first 17 A digit number plus the last digit or letter "X". If the format of the ID number is correct, use a certain algorithm to calculate the check code $check_code and compare it with the last digit of the ID number.

Summary

This article introduces how to use PHP regular expressions to verify the accuracy of ID number. The ID number is the only personal identification, so when developing a website, verification of the ID number is very important. Through the introduction of this article, I believe that everyone can easily use PHP regular expressions to verify ID numbers.

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