python-regexHow to use quantifiers in Python regex?

Quantifiers are used in Python regex to specify the number of times a character, group, or character class can appear in the searched text.

For example, the regex a{2,4} will match any string that contains between 2 and 4 a characters.

import re

# Match strings with between 2 and 4 a characters
pattern = re.compile(r'a{2,4}')

# Test strings
test_strings = ['aa', 'aaa', 'aaaa', 'aaaaa']

# Print matches
for test_string in test_strings:
    if pattern.search(test_string):
        print('{} matches'.format(test_string))
    else:
        print('{} does not match'.format(test_string))

Output example

aa matches
aaa matches
aaaa matches
aaaaa does not match

The code above uses the re.compile() function to create a regex pattern object, and the pattern.search() method to search for matches in the test strings. The {2,4} quantifier specifies that the pattern should match strings with between 2 and 4 a characters.

Parts of the code:

• re.compile(r'a{2,4}'): creates a regex pattern object that will match strings with between 2 and 4 a characters
• pattern.search(test_string): searches for matches in the test strings
• {2,4}: quantifier that specifies the number of times the character, group, or character class can appear in the searched text

Helpful links

• Python Regex Cheat Sheet
• Python Regex Tutorial

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