How to use PHP regular expression to verify the validity of ID number

When developing an application that requires the input of an ID number, it is very important to ensure the validity of the entered ID number. This article will introduce how to use PHP regular expressions to verify the validity of the ID number.

What is an ID number?

The ID card number is used to identify residents of China (Mainland). It is a personal identification number composed of 18 digits and letters.

The structure of the ID number

The ID number consists of 18 digits and letters, the first digit is a digit, indicating the province or municipality where it is located, and the second to sixth digits are digits. , indicating the region, the seventh to fourteenth digits are date codes, indicating the date of birth, the fifteenth to seventeenth digits are numbers, indicating the code of the local police station, and the eighteenth digit is a number or letter, according to Calculated by an algorithm and used to verify the correctness of the ID number.

Use regular expressions to verify the validity of ID numbers

Regular expressions are a language that describes string patterns and can be used to retrieve, replace, and separate strings. Use PHP regular expressions to verify the validity of the ID number.

The following are some basic ID number verification rules:

1. The ID number is composed of 18 digits and letters.

2. The first to sixth digits of the ID number indicate the region where you are located and comply with the prescribed administrative division code.

3. The seventh to fourteenth digits of the ID card number indicate the date of birth, and are consistent with the legality of the date.

4. The 15th to 17th digits of the ID number represent the code of the local police station.

5. The last digit in the ID number is the check code, which can be calculated through an algorithm.

According to the above rules, the regular expression is divided into the following parts:

1. The length of the ID number is 18 digits.

2. The first to sixth digits of the ID number are numbers or letters.

3. The seventh to fourteenth digits of the ID number are numbers and conform to the legality of the date.

4. The 15th to 17th digits of the ID number are numbers.

5. The last digit in the ID number is a number or letter.

According to the above rules, you can write the following PHP regular expression code:

function validate_id_card($id_card){
    //身份证号码的长度为18位
    if(strlen($id_card)!=18){
        return false;
    }
    
    //身份证号码中第一位至第六位是数字或字母
    $pattern='/^[0-9a-zA-Z]{6}/';
    if(!preg_match($pattern, substr($id_card,0,6))){
        return false;
    }
    
    //身份证号码中第七位至第十四位是数字，且符合日期的合法性
    $date=substr($id_card,6,8);  
    if(!is_numeric($date)){  
        return false;  
    }
    $year=(int)substr($date,0,4);  
    $month=(int)substr($date,4,2);  
    $day=(int)substr($date,6,2);  
    if(!checkdate($month,$day,$year)){  
        return false;  
    }
    
    //身份证号码中第十五位至第十七位是数字
    $pattern='/^d{3}/';
    if(!preg_match($pattern, substr($id_card, 14, 3))){
        return false;
    }
    
    //身份证号码中最后一位是数字或字母
    $pattern='/^[0-9a-zA-Z]{1}/';
    if(!preg_match($pattern, substr($id_card, 17, 1))){
        return false;
    }
    
    //校验码验证
    $digit_array=array(1,0,'X',9,8,7,6,5,4,3,2);
    $check_sum=0;
    for($i=0;$i<17;$i++){
        $check_sum += substr($id_card,$i,1)*$digit_array[$i];
    }
    $mod=$check_sum%11;
    $verify_code=$digit_array[$mod];
    if($verify_code != strtoupper(substr($id_card,17))){
        return false;
    }
    
    return true;
}

Code description:

• Lines 1 to 21 define a name It is the function of "validate_id_card", used to verify the validity of the ID number. The function receives a $id_card parameter, which is the ID number.
• Line 3 verifies that the length of the ID number is 18 digits.
• Lines 6 to 10 verify that the first to sixth digits of the ID number are numbers or letters.
• Lines 13 to 22 verify that the seventh to fourteenth digits of the ID number are numbers and check whether the date is legal.
• Lines 25 to 29 verify that the 15th to 17th digits of the ID number are numbers.
• Lines 32 to 36 verify that the last digit in the ID number is a number or letter.
• Lines 39 to 50 verify whether the check code of the ID number is correct.

Usage Example

Here's how to use this function in PHP:

$id_card='510722199091231234';
if(validate_id_card($id_card)){
    echo $id_card.' 是有效的身份证号码';
}
else{
    echo $id_card.' 不是有效的身份证号码';
}

Output:

510722199091231234 是有效的身份证号码

Summary

Through the above PHP regular expression code and usage examples, we can realize the validity verification of the ID card number. When developing applications that use ID numbers, it is very important to ensure the legitimacy of the ID numbers to avoid exceptions and errors caused by incorrect data input.

The above is the detailed content of How to use PHP regular expression to verify the validity of ID number. For more information, please follow other related articles on the PHP Chinese website!