Escaping Special Characters

Special characters (like the character class brackets \[ and \] below) are not matched literally:

match = re.search(r'[b]', 'a[b]c')
match.group()
# Out: 'b'

By escaping the special characters, they can be matched literally:

match = re.search(r'\[b\]', 'a[b]c')
match.group()
# Out: '[b]'

The re.escape() function can be used to do this for you:

re.escape('a[b]c')
# Out: 'a\\[b\\]c'
match = re.search(re.escape('a[b]c'), 'a[b]c')
match.group()
# Out: 'a[b]c'

The re.escape() function escapes all special characters, so it is useful if you are composing a regular expression based on user input:

username = 'A.C.'  # suppose this came from the user
re.findall(r'Hi {}!'.format(username), 'Hi A.C.! Hi ABCD!')
# Out: ['Hi A.C.!', 'Hi ABCD!']
re.findall(r'Hi {}!'.format(re.escape(username)), 'Hi A.C.! Hi ABCD!')
# Out: ['Hi A.C.!']

Found a mistake? Have a question or improvement idea? Let me know.

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