Python:
Using regular expressions

How to:

Using regex in Python involves the re module, which provides a set of functions to process text using regular expressions.

Basic Pattern Matching

To search for a pattern in a string, use re.search(). It returns a match object when the pattern is found, else None.

import re

text = "Learn Python programming"
match = re.search("Python", text)
if match:
    print("Pattern found!")
else:
    print("Pattern not found.")

Output:

Pattern found!

Compiling Regular Expressions

For repeated use of the same pattern, compile it first with re.compile() for better performance.

pattern = re.compile("Python")
match = pattern.search("Learn Python programming")
if match:
    print("Compiled pattern found!")

Output:

Compiled pattern found!

Splitting Strings

To split a string at each match of a regex pattern, use re.split().

result = re.split("\s", "Python is fun")
print(result)

Output:

['Python', 'is', 'fun']

Finding All Matches

To find all non-overlapping occurrences of a pattern, use re.findall().

matches = re.findall("n", "Python programming")
print(matches)

Output:

['n', 'n']

Replacing Text

Use re.sub() to replace occurrences of a pattern with a new string.

replaced_text = re.sub("fun", "awesome", "Python is fun")
print(replaced_text)

Output:

Python is awesome

Third-Party Libraries

While Python’s built-in re module is powerful, third-party libraries like regex offer more features and enhanced performance. To use regex, install it via pip (pip install regex) and import it in your code.

import regex

text = "Learning Python 3.8"
match = regex.search(r"Python\s(\d+\.\d+)", text)
if match:
    print(f"Found version: {match.group(1)}")

Output:

Found version: 3.8