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revision 461 by ph10, Mon Oct 5 10:59:35 2009 UTC revision 579 by ph10, Wed Nov 24 17:39:25 2010 UTC
# Line 18  DIFFERENCES BETWEEN PCRE AND PERL Line 18  DIFFERENCES BETWEEN PCRE AND PERL
18  <P>  <P>
19  This document describes the differences in the ways that PCRE and Perl handle  This document describes the differences in the ways that PCRE and Perl handle
20  regular expressions. The differences described here are with respect to Perl  regular expressions. The differences described here are with respect to Perl
21  5.10.  versions 5.10 and above.
22  </P>  </P>
23  <P>  <P>
24  1. PCRE has only a subset of Perl's UTF-8 and Unicode support. Details of what  1. PCRE has only a subset of Perl's UTF-8 and Unicode support. Details of what
# Line 102  strings when part of a pattern is repeat Line 102  strings when part of a pattern is repeat
102  the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b".  the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b".
103  </P>  </P>
104  <P>  <P>
105  11. PCRE does support Perl 5.10's backtracking verbs (*ACCEPT), (*FAIL), (*F),  11. PCRE's handling of duplicate subpattern numbers and duplicate subpattern
 (*COMMIT), (*PRUNE), (*SKIP), and (*THEN), but only in the forms without an  
 argument. PCRE does not support (*MARK).  
 </P>  
 <P>  
 12. PCRE's handling of duplicate subpattern numbers and duplicate subpattern  
106  names is not as general as Perl's. This is a consequence of the fact the PCRE  names is not as general as Perl's. This is a consequence of the fact the PCRE
107  works internally just with numbers, using an external table to translate  works internally just with numbers, using an external table to translate
108  between numbers and names. In particular, a pattern such as (?|(?&#60;a&#62;A)|(?&#60;b)B),  between numbers and names. In particular, a pattern such as (?|(?&#60;a&#62;A)|(?&#60;b)B),
# Line 118  names map to capturing subpattern number Line 113  names map to capturing subpattern number
113  an error is given at compile time.  an error is given at compile time.
114  </P>  </P>
115  <P>  <P>
116    12. Perl recognizes comments in some places that PCRE doesn't, for example,
117    between the ( and ? at the start of a subpattern.
118    </P>
119    <P>
120  13. PCRE provides some extensions to the Perl regular expression facilities.  13. PCRE provides some extensions to the Perl regular expression facilities.
121  Perl 5.10 includes new features that are not in earlier versions of Perl, some  Perl 5.10 includes new features that are not in earlier versions of Perl, some
122  of which (such as named parentheses) have been in PCRE for some time. This list  of which (such as named parentheses) have been in PCRE for some time. This list
# Line 187  Cambridge CB2 3QH, England. Line 186  Cambridge CB2 3QH, England.
186  REVISION  REVISION
187  </b><br>  </b><br>
188  <P>  <P>
189  Last updated: 04 October 2009  Last updated: 31 October 2010
190  <br>  <br>
191  Copyright &copy; 1997-2009 University of Cambridge.  Copyright &copy; 1997-2010 University of Cambridge.
192  <br>  <br>
193  <p>  <p>
194  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.

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