Python Regular Expression

import re
my_string="Your birth day is on 24-12-2002"
dt=re.search("([0-9]{2}\-[0-9]{2}\-[0-9]{4})", my_string)
print(dt[1])

24-12-2002

Links ( URLs) from a file

import re
path='C:/dir_name/string_functions.php' # path of the file to read
fob=open(path,'r') # Open in read mode 
data=fob.read() # collect data 
fob.close() # close file object 
#print(data)     
urls1 = re.findall(r'href=[\'"]?([^\'" >]+)', data)
print(urls1)

urls1 = re.findall(r'href=[\'"]?([^\'" >]+)', data,re.IGNORECASE)

Searching string

import re
if re.search('PLUS', 'Welcome to plus2net.com', re.IGNORECASE):
    print('It is there') # True 
else:
    print('It is NOT there') # False

It is there

Additional Examples and Use Cases for Python Regular Expressions

Example: Extracting Email Addresses from Text

We can use regular expressions to identify and extract email addresses from a string. This is useful for tasks like data cleaning or web scraping.

import re
text = "Contact us at support@example.com or sales@example.co.uk"
emails = re.findall(r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,7}\b', text)
print(emails)

['support@example.com', 'sales@example.co.uk']

Use Case: Validating Strong Passwords

We can enhance the user experience by implementing regular expressions to validate the complexity of user-entered passwords.

import re
password = "P@ssw0rd123"
if re.match(r'^(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*[@#$%^&+=]).{8,}$', password):
    print("Password is strong")
else:
    print("Password is weak")

Password is strong

Advanced Feature: Using `re.sub` to Replace Patterns

The re.sub() method allows us to search for patterns and replace them. This is beneficial when sanitizing or formatting text.

import re
text = "Visit https://www.example.com or http://example.org"
updated_text = re.sub(r'https?://\S+', '[LINK]', text)
print(updated_text)

Visit [LINK] or [LINK]

Example: Splitting Strings by Multiple Delimiters

Regular expressions can be used to split a string based on multiple delimiters. This is useful for parsing CSV-like strings.

import re
data = "apple;banana,orange:grape"
fruits = re.split(r'[;,:]', data)
print(fruits)

['apple', 'banana', 'orange', 'grape']

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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