Feature: Quantifiers

^{Home | Features | Improve this section}

Quantifiers specify repetition of an Atom. By default, quantifiers are “greedy” in that they attempt to match as many instances of the preceding Atom as possible to satisfy the pattern before backtracking.

Syntax

^{Improve this section}

NOTE: The following syntax is an example based on some of the supported engines. For specific engine support, see Engines.

• * — Matches the preceding Atom zero or more times. Example: a*b matches b, ab, aab, aaab, etc.
• + — Matches the preceding Atom one or more times. Example: a+b matches ab, aab, aaab, etc., but not b.
• ? — Matches the preceding Atom zero or one times. Example: a?b matches b, ab.
• {n} — Where n is an integer. Matches the preceding Atom exactly n times. Example: a{2} matches aa but not a or aaa.
• {n,} — Where n is an integer. Matches the preceding Atom at-least n times. Example: a{2,} matches aa, aaa, aaaa, etc., but not a.
• {n,m} — Where n and m are integers, and m >= n. Matches the preceding Atom at-least n times and at-most m times. Example: a{2,3} matches aa, aaa, aaaa, etc., but not a or aaaa.

Engines

Engine	Supported
Perl	✔
PCRE	✔
Boost.Regex	✔
.NET	✔
Oniguruma	✔
Hyperscan	✔
ICU	✔
Glib/GRegex	✔
ECMAScript	✔

See Also

^{Improve this section}

• Lazy Quantifiers
• Possessive Quantifiers