How to use Python regular expressions for ID number verification

ID card number is an identification symbol that we often use in our daily life. When processing some data related to identity information, it is often necessary to verify the ID number to ensure its legitimacy. Python's regular expression is a very convenient and efficient tool that can be used to quickly verify ID numbers. This article will introduce how to use Python regular expressions for ID number verification.

1. The basic format of the ID number

Before we start writing regular expressions, we need to first understand the basic format of the ID number. The Chinese resident identity card number consists of 18 digits, of which the first 17 digits are the code for the region and date of birth, and the 18th digit is the check code. The specific format is as follows:

1. The first 1-6 digits are the address code, indicating the administrative area where the household registration is located; the 7-14 digits of
2. are the date, month and day of birth code, indicating the person date of birth; the 15th to 17th digits of
3. are the sequence code, indicating the sequence number of the ID card in the address code area; the 18th digit of
4. is the check code, used to Check whether the entire ID card number meets the specifications.

2. Use Python regular expressions to verify ID numbers

Next we will introduce how to use Python regular expressions to verify ID numbers.

(1) Introducing the re module

When using Python to write and match regular expressions, you need to introduce the re module first. The syntax is as follows:

import re

(2 ) Writing regular expressions

When writing regular expressions for ID numbers, you need to pay attention to the following points:

1. The length of the ID number must be 18 digits, otherwise it will be judged as invalid;
2. The first 17 digits must be numbers, and the last digit can be a number or the letter The sum result is divided by 11, and the number corresponding to the remainder is the check code. If the remainder is 10, the check code is the letter X.
Based on the above factors, we can write the following regular expression:

pattern = r'^[1-9]d{5}[1-9]d{3}(0[1-9]|1[0-2])(0[1-9]|[1-2]d|3[0-1])d{3}[dX]$'

Among them, r represents that the string is an original string, ^ represents the beginning of the matching string, $ represents the end of the matching string, [] represents the matching range, d represents matching numeric characters, {n} represents matching n leading characters, | represents matching multiple patterns, and X represents the letter X (capital case required).

(3) Use the re module for matching

After writing the regular expression, we can use the match() function in the re module to match. The syntax is as follows:

re.match(pattern, string, flags=0)

Among them, pattern is a regular expression, string is the string that needs to be matched, and the flags parameter can set the matching mode (re.IGNORECASE is commonly used to indicate ignoring case).

A complete Python code example is given below:

import re

id_card = '110101198001011234' # 待验证的身份证号
pattern = r'^[1-9]d{5}[1-9]d{3}(0[1-9]|1[0-2])(0[1-9]|[1-2]d|3[0-1])d{3}[dX]$'

if re.match(pattern, id_card):
    print('该身份证号合法！')
else:
    print('该身份证号不合法！')

Run the above code, the output result is "The ID number is legal!", indicating that the ID number is in compliance with the specifications.

3. Summary

This article mainly introduces how to use Python regular expressions for ID number verification. In practical applications, we can adjust regular expressions as needed to adapt to different data validation requirements. At the same time, we also need to pay attention to the writing and matching efficiency of regular expressions to ensure the performance and stability of the program.

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