between M and N occurences.

Other flavours use RE\{M\} etc.

Perl provides several "quote-like" operators for writing REs, including the common // form and less common ??.

A comprehensive survey of regexp flavours is found in Friedl 1997 (see below).

[Jeffrey E.F. Friedl, "Mastering Regular Expressions, O'Reilly, 1997].

2. Any description of a pattern composed from combinations of symbols and the three operators:

Concatenation - pattern A concatenated with B matches a match for A followed by a match for B.

Or - pattern A-or-B matches either a match for A or a match for B.

Closure - zero or more matches for a pattern.

The earliest form of regular expressions (and the term itself) were invented by mathematician Stephen Cole Kleene in the mid-1950s, as a notation to easily manipulate "regular sets", formal descriptions of the behaviour of finite state machines, in regular algebra.

[S.C. Kleene, "Representation of events in nerve nets and finite automata", 1956, Automata Studies. Princeton].

[J.H. Conway, "Regular algebra and finite machines", 1971, Eds Chapman & Hall].

[Sedgewick, "Algorithms in C", page 294].

Last updated: 2015-04-30

Nearby terms:

between M and N occurences. pattern A concatenated with B matches a match

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