रेगेक्स की मूल बातें

import re
print(re.findall(r'\d+', 'abc 123 def 456'))

import re
print(re.search(r'cat', 'the cat sat'))

import re
print(re.findall(r'c.t', 'cat cut c9t caaat'))

import re
print(re.findall(r'[aeiou]', 'hello world'))

import re
print(re.findall(r'\d{2,4}', '1 12 123 1234 12345'))

import re
print(re.findall(r'^\w+', 'hello world'))
print(re.findall(r'\b\w{4}\b', 'cat cats come home'))

import re
print(re.findall(r'\w+', 'hello, world!'))

import re
print(re.findall(r'cat|dog', 'I have a cat and a dog'))

import re
html = '<b>bold</b> and <i>italic</i>'
print(re.findall(r'<.*>', html))   # greedy
print(re.findall(r'<.*?>', html))  # lazy

import re
# Without r: '\\d+' is needed
# With r:    '\d+' is sufficient
print(re.findall(r'\d+', 'abc123'))