The Rest of the Metacharacters

• {m,n} is straightforward now

• It's like * but keeps track of the number of matches

• P{n} is the same as P{n,n}

• Because it keeps track of the number in a small integer, m and n are restricted to be between 0 and 32767.

• There's a non-greedy version {m,n}? which is rarely used

• Actually X* is implemented with {m,n} for nontrivial X.

• This means that ^(foo|bar)*$ wouldn't match "foo" x 35000.

  • Actually the regex engine would run out of stack and dumps core before that

• Sometime after 5.004_04 and at or before 5.005_02, this was fixed

  • n=32767 now has a special meaning; it is used internally to mean infinity

  • You are no longer allowed to specify 32767 explicitly

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Copyright © 2002 M. J. Dominus