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<html>
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<head>
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<title>pcrelimits specification</title>
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</head>
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<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
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<h1>pcrelimits man page</h1>
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<p>
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Return to the <a href="index.html">PCRE index page</a>.
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</p>
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<p>
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This page is part of the PCRE HTML documentation. It was generated automatically
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from the original man page. If there is any nonsense in it, please consult the
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man page, in case the conversion went wrong.
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<br>
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<br><b>
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SIZE AND OTHER LIMITATIONS
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</b><br>
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<P>
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There are some size limitations in PCRE but it is hoped that they will never in
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practice be relevant.
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</P>
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<P>
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The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE is
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compiled with the default internal linkage size of 2. If you want to process
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regular expressions that are truly enormous, you can compile PCRE with an
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internal linkage size of 3 or 4 (see the <b>README</b> file in the source
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distribution and the
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<a href="pcrebuild.html"><b>pcrebuild</b></a>
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documentation for details). In these cases the limit is substantially larger.
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However, the speed of execution is slower.
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</P>
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<P>
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All values in repeating quantifiers must be less than 65536.
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</P>
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<P>
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There is no limit to the number of parenthesized subpatterns, but there can be
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no more than 65535 capturing subpatterns.
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</P>
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<P>
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The maximum length of name for a named subpattern is 32 characters, and the
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maximum number of named subpatterns is 10000.
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</P>
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<P>
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The maximum length of a subject string is the largest positive number that an
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integer variable can hold. However, when using the traditional matching
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function, PCRE uses recursion to handle subpatterns and indefinite repetition.
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This means that the available stack space may limit the size of a subject
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string that can be processed by certain patterns. For a discussion of stack
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issues, see the
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<a href="pcrestack.html"><b>pcrestack</b></a>
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documentation.
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</P>
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<br><b>
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AUTHOR
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</b><br>
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<P>
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Philip Hazel
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<br>
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University Computing Service
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<br>
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Cambridge CB2 3QH, England.
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<br>
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</P>
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<br><b>
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REVISION
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</b><br>
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<P>
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Last updated: 24 August 2011
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<br>
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Copyright © 1997-2011 University of Cambridge.
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<br>
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<p>
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Return to the <a href="index.html">PCRE index page</a>.
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</p>
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