Regular expression
A regular expression (shortened as regex or regexp), sometimes referred to as rational expression, is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for “find” or “find and replace” operations on strings, or for input validation.
Regular expression techniques are developed in theoretical computer science and formal language theory. They are used in search engines, in search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK, and in lexical analysis. Regular expressions are also supported in many programming languages.
Different syntaxes for writing regular expressions have existed since the 1980s, one being the POSIX standard and another, widely used, being the Perl syntax.
- GitHub: https://github.com/topics/regular-expression
- Wikipedia: https://en.wikipedia.org/wiki/Regular_expression
- Created by: Stephen Cole Kleene
- Released: 1950
- Related Topics: pattern-matching, wildcard, glob, grep, awk, sed,
- Aliases: regex, regexp, regular-expressions,
- Last updated: 2026-06-11 00:26:10 UTC
- JSON Representation
https://github.com/samliebl/regex-map-replace
Run a text string through an array of individual match-replace regular expressions.
map match regex regexp regular-expression replace replace-text string-formatter
Last synced: 14 Mar 2025
https://github.com/faraazarsath/user-registration-login
This Python script provides a simple user registration system with username and password validation using regular expressions. It also includes a password recovery option.
filehandling if-else python regular-expression
Last synced: 29 Apr 2026
