Regular Expression, also known as Regex or RegExp, refers to a type of pattern “used to match character combinations in strings”[1]. It is a very powerful tool for searching, matching, replacing, and parsing target text based on specific patterns. In other words, a regex engine[2] can find, extract and substitute target text under a format defined by a given regex.
Regex is not universally the same. Different flavours of regex are supported by different regex engines provided by different libraries and programming languages. However, a portion of the syntax is generally the same across them.[3]
Usage
Regex is used in many text processing tools. Graphical examples include the find and replace feature in LibreOffice[4]. Command line examples include AWK, sed, and grep.
Many popular scripting and programming languages provide built-in support for regex, notably JavaScript, Perl, Java, Ruby, Python, C++, PHP, each with slighting varying implementations and different sets of supported syntax.[5]
See Also
References
- ↑ Regular expressions - JavaScript, MDN, 2025 (Accessed 2025-06-20)
- ↑ How a Regex Engine Works Internally, Jan Goyvaerts, 2019 (Accessed: 2025-06-20)
- ↑ regex101: build, test, and debug regex, regex101.com, 2025 (Accessed: 2025-06-20)
- ↑ Using Regular Expressions in Text Searches, LibreOffice, 2025 (Accessed: 2025-06-20)
- ↑ Popular Tools, Utilities and Programming Languages That Support Regular Expressions, Jan Goyvaerts, 2021 (Accessed: 2025-06-21)