regex matxh a string python code example

Example 1: python regular expression

import re

# The string you want to find a pattern within
test_string = 'Hello greppers!'

# Creating a regular expression pattern
# This is a simple one which finds "Hello"
pattern = re.compile(r'Hello')

# This locates and returns all the occurences of the pattern
# within the test_string
match = pattern.finditer(test_string)

# Outputs all the ocurrences which were returned as 
# as match objects
for match in matches:
  print(match)

Example 2: python re.search()

## Search for pattern 'bb' in string 'aabbcc'.
  ## All of the pattern must match, but it may appear anywhere.
  ## On success, match.group() is matched text.
  match = re.search(r'bb', 'aabbcc') # found, match.group() == "bb"
  match = re.search(r'cd', 'aabbcc') # not found, match == None

  ## . = any char but \n
  match = re.search(r'...c', 'aabbcc') # found, match.group() == "abbc"

  ## \d = digit char, \w = word char
  match = re.search(r'\d\d\d', 'p123g') # found, match.group() == "123"
  match = re.search(r'\w\w\w', '@@abcd!!') # found, match.group() == "abc"

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