| 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. |
5.10/5.11. |
| 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 |
| 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 (?|(?<a>A)|(?<b)B), |
between numbers and names. In particular, a pattern such as (?|(?<a>A)|(?<b)B), |
| 113 |
an error is given at compile time. |
an error is given at compile time. |
| 114 |
</P> |
</P> |
| 115 |
<P> |
<P> |
| 116 |
13. PCRE provides some extensions to the Perl regular expression facilities. |
12. PCRE provides some extensions to the Perl regular expression facilities. |
| 117 |
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 |
| 118 |
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 |
| 119 |
is with respect to Perl 5.10: |
is with respect to Perl 5.10: |
| 182 |
REVISION |
REVISION |
| 183 |
</b><br> |
</b><br> |
| 184 |
<P> |
<P> |
| 185 |
Last updated: 04 October 2009 |
Last updated: 12 May 2010 |
| 186 |
<br> |
<br> |
| 187 |
Copyright © 1997-2009 University of Cambridge. |
Copyright © 1997-2010 University of Cambridge. |
| 188 |
<br> |
<br> |
| 189 |
<p> |
<p> |
| 190 |
Return to the <a href="index.html">PCRE index page</a>. |
Return to the <a href="index.html">PCRE index page</a>. |