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.TH PCRECOMPAT 3 | .TH PCRECOMPAT 3 "08 January 2012" "PCRE 8.30" |
.SH NAME |
.SH NAME |
PCRE - Perl-compatible regular expressions |
PCRE - Perl-compatible regular expressions |
.SH "DIFFERENCES BETWEEN PCRE AND PERL" |
.SH "DIFFERENCES BETWEEN PCRE AND PERL" |
Line 8 This document describes the differences in the ways th
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Line 8 This document describes the differences in the ways th
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regular expressions. The differences described here are with respect to Perl |
regular expressions. The differences described here are with respect to Perl |
versions 5.10 and above. |
versions 5.10 and above. |
.P |
.P |
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 Unicode support. Details of what it does |
it does have are given in the | have are given in the |
.\" HREF |
.\" HREF |
\fBpcreunicode\fP |
\fBpcreunicode\fP |
.\" |
.\" |
Line 95 in the
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Line 95 in the
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.\" |
.\" |
page. |
page. |
.P |
.P |
11. If (*THEN) is present in a group that is called as a subroutine, its action | 11. If any of the backtracking control verbs are used in an assertion or in a |
is limited to that group, even if the group does not contain any | characters. | subpattern that is called as a subroutine (whether or not recursively), their |
| effect is confined to that subpattern; it does not extend to the surrounding |
| pattern. This is not always the case in Perl. In particular, if (*THEN) is |
| present in a group that is called as a subroutine, its action is limited to |
| that group, even if the group does not contain any | characters. There is one |
| exception to this: the name from a *(MARK), (*PRUNE), or (*THEN) that is |
| encountered in a successful positive assertion \fIis\fP passed back when a |
| match succeeds (compare capturing parentheses in assertions). Note that such |
| subpatterns are processed as anchored at the point where they are tested. |
.P |
.P |
12. There are some differences that are concerned with the settings of captured |
12. There are some differences that are concerned with the settings of captured |
strings when part of a pattern is repeated. For example, matching "aba" against |
strings when part of a pattern is repeated. For example, matching "aba" against |
Line 114 an error is given at compile time.
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Line 122 an error is given at compile time.
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.P |
.P |
14. Perl recognizes comments in some places that PCRE does not, for example, |
14. Perl recognizes comments in some places that PCRE does not, for example, |
between the ( and ? at the start of a subpattern. If the /x modifier is set, |
between the ( and ? at the start of a subpattern. If the /x modifier is set, |
Perl allows whitespace between ( and ? but PCRE never does, even if the | Perl allows white space between ( and ? but PCRE never does, even if the |
PCRE_EXTENDED option is set. |
PCRE_EXTENDED option is set. |
.P |
.P |
15. PCRE provides some extensions to the Perl regular expression facilities. |
15. PCRE provides some extensions to the Perl regular expression facilities. |
Line 154 by the PCRE_BSR_ANYCRLF option.
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Line 162 by the PCRE_BSR_ANYCRLF option.
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different hosts that have the other endianness. However, this does not apply to |
different hosts that have the other endianness. However, this does not apply to |
optimized data created by the just-in-time compiler. |
optimized data created by the just-in-time compiler. |
.sp |
.sp |
(k) The alternative matching function (\fBpcre_dfa_exec()\fP) matches in a | (k) The alternative matching functions (\fBpcre_dfa_exec()\fP and |
different way and is not Perl-compatible. | \fBpcre16_dfa_exec()\fP) match in a different way and are not Perl-compatible. |
.sp |
.sp |
(l) PCRE recognizes some special sequences such as (*CR) at the start of |
(l) PCRE recognizes some special sequences such as (*CR) at the start of |
a pattern that set overall options that cannot be changed within the pattern. |
a pattern that set overall options that cannot be changed within the pattern. |
Line 175 Cambridge CB2 3QH, England.
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Line 183 Cambridge CB2 3QH, England.
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.rs |
.rs |
.sp |
.sp |
.nf |
.nf |
Last updated: 14 November 2011 | Last updated: 01 June 2012 |
Copyright (c) 1997-2011 University of Cambridge. | Copyright (c) 1997-2012 University of Cambridge. |
.fi |
.fi |