Py Regex Practical — Free Python Tutorial

TL;DR: Learn Py Regex Practical in Python with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

Py Regex Practical in Python

Regular expressions (regex) are patterns that describe text — they let you search, validate, extract, and replace complex string patterns with a single expressive rule.

Core pattern syntax: . (any char), \d (digit), \w (word char), \s (whitespace), ^ (start), $ (end), * (0+), + (1+), ? (0 or 1), {n,m} (n to m times). Square brackets [abc] match any of a, b, c.

Capturing groups (...) extract matched sub-patterns. Named groups (?P<name>...) make extractions self-documenting. Non-capturing groups (?:...) group without capturing.

Key functions: re.search() finds first match anywhere; re.match() matches at start only; re.findall() returns all matches as a list; re.sub() replaces matches; re.compile() pre-compiles a pattern for reuse.

import re

re.search(r'\d+', text)       # first match → Match object
re.findall(r'\d+', text)      # all matches → list
re.sub(r'\s+', ' ', text)     # replace
re.split(r'[,;]', text)        # split on , or ;

m = re.search(r'(\w+)@(\w+)', text)
m.group(0)   # full match
m.group(1)   # first group

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