Python RegEx or Regular Expression

In Python, “RegEx” or “Regular Expression” is a powerful tool for pattern matching and manipulation of strings. RegEx provides a concise and flexible way to match and extract patterns from strings. It uses a syntax based on special characters and metacharacters to define the pattern to be searched for in the input string.

Here are some of the most common metacharacters used in Python RegEx:

  1. . (dot) – Matches any character except a newline.
  2. ^ (caret) – Matches the start of a string.
  3. $ (dollar) – Matches the end of a string.
  4. * (asterisk) – Matches zero or more occurrences of the preceding character.
  5. + (plus) – Matches one or more occurrences of the preceding character.
  6. ? (question mark) – Matches zero or one occurrence of the preceding character.
  7. {m,n} – Matches at least m and at most n occurrences of the preceding character.
  8. [] (square brackets) – Matches a set of characters.
  9. | (vertical bar) – Matches either the expression before or the expression after the bar.
  10. () (parentheses) – Groups a set of characters as a single unit.

To perform RegEx operations in Python, you need to import the re module. Some of the most common functions in the re module include search(), findall(), split(), sub(), and compile().

Here’s an example that demonstrates the use of the search() function to find the first match of a pattern in a string:

import re
text = “The quick yellow tiger jumps over the lazy deer.”
pattern = “tiger”
match =, text)

if match:
print(“Match found at index”, match.start(), “to”, match.end(), “:”,
print(“No match found.”)

This code will output:

Match found at index 17 to 22 : tiger

Disclaimer: The information provided on the blog is for educational and informational purposes only. It should not be considered as a substitute for professional advice.


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