Overview
Regular Expressions, commonly abbreviated as Regex, are sequences of characters that define a search pattern. They are used extensively in programming, data validation, search operations, and text processing.Syntax and Patterns
Basic Elements Character Classes
Symbol | Description |
. | Matches any character except a newline |
^ | Anchors the match at the beginning of a string |
$ | Anchors the match at the end of a string |
* | Matches 0 or more repetitions |
+ | Matches 1 or more repetitions |
? | Matches 0 or 1 occurrence |
[] | Matches any one character within the brackets |
[^] | Matches any character not in the brackets |
{n} | Matches exactly n occurrences |
{n,} | Matches at least n occurrences |
{n,m} | Matches between n and m occurrences |
Character Classes
Class | Matches |
\d | Any digit (0-9) |
\D | Any non-digit |
\w | Any word character (alphanumeric + underscore) |
\W | Any non-word character |
\s | Any whitespace character |
\S | Any non-whitespace character |
Common Examples
1. Email Validation
^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-z]{2,}$Matches: [email protected], [email protected]
2. Extract Numbers
\d+Matches: Any sequence of digits like 123, 45678
3. Indian Mobile Number Validation
^[6-9]\d{9}$Matches: 9876543210, 9123456789
4. PAN Number (India) Validation
^[A-Z]{5}[0-9]{4}[A-Z]{1}$Matches: ABCDE1234F
5. Date in dd-mm-yyyy or dd/mm/yyyy Format
^(0[1-9]|[12][0-9]|3[01])[-/](0[1-9]|1[0-2])[-/](19|20)\d{2}$Matches: 21-04-2025, 01/01/2000
6. Detect Purchase Intent Keywords
\b(interested|purchase|buy)\bMatches: Any standalone occurrence of "interested", "purchase", or "buy" (e.g., "I am interested", "ready to purchase", "want to buy")
Online Regex Testing Tools
To fully unlock the power of regex, it's encouraged to explore more through hands-on practice and self-research. Many complex patterns and use cases can be discovered by experimenting and searching specific scenarios online.