Regular expressions originated in 1951, when mathematician Stephen Cole Kleene described regular languages using his mathematical notation called regular events. These arose in See more

A regular expression, often called a pattern, specifies a set of strings required for a particular purpose. A simple way to specify a finite set of strings is to list its elements or members. However, there are often more concise ways: for example, the set containing the … See more

A regex pattern matches a target string. The pattern is composed of a sequence of atoms. An atom is a single point within the regex pattern which it tries to match to the target string. The … See more

There are at least three different algorithms that decide whether and how a given regex matches a string.
The oldest and … See more

The phrase regular expressions, or regexes, is often used to mean the specific, standard textual syntax for representing … See more

Regular expressions describe regular languages in formal language theory. They have the same expressive power as regular grammars See more

Many features found in virtually all modern regular expression libraries provide an expressive power that exceeds the regular languages. … See more