How to validate postal code format using regular expressions in PHP

With the development of the Internet, we increasingly need to use postal codes for address identification and interaction. In PHP, using regular expressions to validate zip code formats is a common approach. This article will introduce how to use regular expressions in PHP to verify the zip code format.

1. Understanding the postal code

The postal code is a numerical or alphanumeric code assigned to the postal address to facilitate delivery by the postman. Postal codes usually consist of numbers, and the postal code formats in different countries and regions are also different. In China, postal codes consist of six digits, such as: 310000. In other countries, postal codes may contain letters or special characters.

2. Use regular expressions to verify the zip code format

Regular expression is a tool used to match strings and can be used to verify whether the zip code conforms to the specified format. In PHP, regular expression matching can be easily done using the preg_match() function.

The following is an example showing how to use regular expressions to verify Chinese postal codes:

<?php
$zipcode = '310000';
if (preg_match('/^[1-9]d{5}$/', $zipcode)) {
    echo '邮政编码格式正确';
} else {
    echo '邮政编码格式不正确';
}
?>

The above code uses the regular expression /^[d]{6}$/ to Match postal codes and use the preg_match() function to match. In this regular expression, ^ and $ represent the beginning and end of the string, [d] represents any number, and {6} represents the number repeated 6 times. Therefore, this regular expression can match any string consisting of six digits.

The preg_match() function returns 1 if the zip code matches the specified format, otherwise it returns 0. Through this return value, we can perform corresponding processing in the code.

3. Extension

The Zheng code is the same as the last number of the ID card number and is derived according to a certain formula.

China's postal code is a unique identification number composed of 7 digits. It provides a unified, bottom-level identification to the postal business system and fund settlement system. The first digit of China's postal code represents the nature of postal services, the second digit represents the main geographical area (or postal management division), the next four digits are the code of the distribution (or collection) area, post office or delivery section, and the last digit is Check code (currently, Arabic numerals with 0~9, > The Zheng code is 513 /68.

No. 66, Zhongshan 8th Road, Liwan District, Guangzhou City, Postcode 510140 -> Zheng code is 206 /25.

1. So, when you need to customize the regular rules to verify the postal code, you can combine it with the national postal code comparison table to formulate it.

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