Find the first occurrence of a pattern anywhere in a string.
How It Works
re.search(pattern, string) scans for a match at any position and returns a Match object or None. A search is unsuitable for complete-field validation because unmatched text before and after the result is allowed.
Step-by-Step Example
import re
matched_number = re.search(r'\d+', 'Ticket REF-204 is ready')
print(matched_number.group() if matched_number else None)
print(matched_number.start() if matched_number else None)Understanding the Example
- The expression "re.search(r'\\d+', 'Ticket REF-204 is ready')" supplies the value stored as 'matched_number'. This value is then used or checked by the later statements.
- The print() call exposes the result so you can compare it with the behavior described above. Check the value and its type when experimenting.
A successful run of this example prints the following output:
204
11Where This Fits in a Real Program
Start by writing down examples that should match and examples that must fail. Check whether you need to locate a substring, match a prefix or validate an entire field; these are different operations. Unicode and escape sequences can also change which characters are matched, so test accented text and empty input.
Practice: Try It Yourself
Use prefixmatch() for the start only and fullmatch() for the whole string.
For this exercise, predict the result before running the changed code. Then explain the difference between the original and modified cases using the actual values, not just whether the program completed.
Further Reading
Read the official Python documentation for complete parameters, return types and exceptions.
Common Beginner Mistakes
- Calling group() when search() returns None or using search() to validate an entire identifier.
- Search a support message for the first number and its location.
Key Takeaways
- Find the first occurrence of a pattern anywhere in a string.
- re.search(pattern, string) scans for a match at any position and returns a Match object or None.
- Apply the demonstrated operation to the practice input and verify its result before depending on it in a larger program.