How to use Python regular expressions for postal code validation

With the popularity of online shopping, zip code has become a very important part of our lives because it is one of the necessary information for express mailing. For developers, verifying the zip code is also one of the things that often needs to be done. This article will introduce how to use Python regular expressions for postal code verification.

First, we need to understand the format of the zip code. In China, postal codes are generally 6 digits, such as 100101, where the first two digits represent the province, autonomous region or municipality, the third digit represents the postal area, and the last three digits represent the specific post office.

Next, we can start using Python for regular matching. Let's first look at the regular expression that matches six digits: ^d{6}$. Among them, ^ and $ represent the start and end of matching respectively, d represents numbers, and {6} represents matching 6 numbers. Therefore, this regular expression can be used to match any six-digit string.

Next, we need to consider how to match cities and districts. According to the above, the code for the province, autonomous region, or municipality has already been determined, so no matching is required. The zip code can be matched through regular expressions: ^[1-9]d{1}$. Among them, ^[1-9] means matching any number between 1 and 9, and {1} means matching a number. Therefore, this regular expression can match any number between 10 and 99.

Finally, we need to match the specific post office code. Post office codes are three digits, so we can use ^d{3}$ to match.

Now, we have obtained three regular expressions for matching provinces, zip codes and post offices. Next, we need to combine them together.

Considering the structure of the postal code, we can combine the three regular expressions to get the final regular expression: ^[1-9]d{5}$, where The first digit represents the province, the second and third digits represent the zip code, and the last three digits represent the post office, which can completely match any zip code information.

The following is a simple Python program that can use this regular expression for postal code verification:

import re

postal_code = input("请输入邮政编码：")
pattern = r"^[1-9]d{5}$"
match = re.match(pattern, postal_code)

if match:
    print("这是一个有效的邮编")
else:
    print("这不是一个有效的邮编")

In the above code, we first let the user enter the postal code, and then use the match function of the re module Make a match. If the match is successful, it means that the input information is in a correct format, otherwise an error message will be returned.

Summary:

By using Python regular expressions for zip code verification, we can quickly and easily verify whether a zip code is valid, which is very important for developers. In the application, we can also use regular expressions to verify other formats, and use the powerful functions of Python to quickly perform data processing, verification and other operations.

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