How to verify bank card format using PHP regular expression

With the continuous popularity of electronic payment, bank cards have become one of the indispensable payment tools in people's lives. However, when conducting bank card transactions, we need to pay attention to whether the format of the bank card number is correct. Regular expressions in PHP can easily perform format verification on bank card numbers. This article will introduce how to use PHP regular expressions to verify bank card format.

1. Understand the structure of the bank card number

Before verifying the format of the bank card, we need to understand the structure of the bank card number. Bank card numbers usually consist of 16 digits, of which the first 6 digits represent the issuing bank identification number (BIN) of the bank card, followed by the 6-9 digit abbreviation of the card number assigned by the issuing bank, and the last digit is verification. Bit. Different bank card types may have different card number lengths, but the general rules are the same. Therefore, when verifying the bank card format, we need to refer to the structure of the bank card.

2. Use PHP regular expressions to verify bank card format

In PHP, we can use the preg_match function to perform regular expression matching. The specific usage is as follows:

preg_match($pattern, $subject);

Among them, $pattern represents the regular expression pattern, and $subject represents the string that needs to be matched.

When verifying the bank card format, we can use the following regular expression:

$pattern = '/d{16}/';

This regular expression pattern represents a sequence of 16 numbers that appear in the matching string, where represents matching Word boundary, d means matching numeric characters, {16} means matching 16 consecutive numeric characters.

We can apply this regular expression pattern to the function that verifies the bank card number, as follows:

function validate_bank_card_number($card_number) {
    $pattern = '/d{16}/';
    if (preg_match($pattern, $card_number)) {
        return true;
    } else {
        return false;
    }
}

The above function validate_bank_card_number accepts a bank card number as a parameter, and calls the preg_match function for regular expression matches and returns the verification result. When the verification passes, it returns true; otherwise it returns false.

3. Other techniques for verifying bank card format

In addition to using regular expressions to verify bank card format, we can also use the following techniques for verification:

1. Luhn algorithm

Luhn algorithm, also known as the modulo 10 algorithm, is a simple verification algorithm. For a bank card number, we can multiply each number by 2, 1, 2, 1, 2, 1... from right to left, and then add the single digits of each number in the result. Finally, take the sum of all single digits modulo 10. If the result is 0, it means the bank card number is legal.

2. Check Digit Calculation

The last digit of the bank card number is the check digit, and the check rule usually uses parity check. The specific method is to arrange the bank card numbers in reverse order, starting from the first number, multiply the even digits by 2, then add the tens and single digits of the result, plus all the odd digits. Finally, the difference between the single digit of the calculated result and 10 is the check digit value. If the calculated check digit is the same as the check digit in the bank card number, it means that the bank card number is legal.

To sum up, using regular expressions to verify bank card format is a simple and fast method. But in actual development, we also need to consider using different verification methods according to different bank card types to ensure the security and accuracy of bank card transactions.

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