Regular Expressions in Python

Python 155 views Nov 05, 2025 2 min read

Regular Expressions in Python

Regular expressions (regex) are used to search, match, and manipulate text patterns in Python. The re module provides all necessary functions.

import re

Function	Description
`re.match(pattern, string)`	Checks for a match at the beginning of the string
`re.search(pattern, string)`	Searches for a match anywhere in the string
`re.findall(pattern, string)`	Returns a list of all matches
`re.split(pattern, string)`	Splits string by occurrences of the pattern
`re.sub(pattern, repl, string)`	Replaces matches with `repl`
`re.compile(pattern)`	Compiles a regex pattern for reuse

Symbol	Meaning
`.`	Any character except newline
`^`	Start of string
`$`	End of string
`*`	0 or more repetitions
`+`	1 or more repetitions
`?`	0 or 1 repetition (optional)
`{n}`	Exactly n repetitions
`{n,m}`	Between n and m repetitions
`[abc]`	Matches a, b, or c
`[^abc]`	Matches any character except a, b, or c
`\d`	Digit (0-9)
`\D`	Non-digit
`\s`	Whitespace (space, tab, newline)
`\S`	Non-whitespace
`\w`	Word character (letters, digits, underscore)
`\W`	Non-word character

Match at beginning:

import re
text = "Python123"
result = re.match(r"Python", text)
print(result.group())  # Python

Search anywhere:

result = re.search(r"\d+", text)
print(result.group())  # 123

Find all matches:

text = "abc 123 def 456"
numbers = re.findall(r"\d+", text)
print(numbers)  # ['123', '456']

Split string:

text = "apple,banana,orange"
fruits = re.split(r",", text)
print(fruits)  # ['apple', 'banana', 'orange']

Substitute text:

text = "Hello 123 World 456"
new_text = re.sub(r"\d+", "#", text)
print(new_text)  # Hello # World #

Using compiled patterns:

pattern = re.compile(r"\d+")
result = pattern.findall("Numbers: 10, 20, 30")
print(result)  # ['10', '20', '30']

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