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revision 1364 by ph10, Sat Oct 5 15:45:11 2013 UTC revision 1369 by ph10, Tue Oct 8 15:06:46 2013 UTC
# Line 1  Line 1 
1  .TH PCREPATTERN 3 "05 October 2013" "PCRE 8.34"  .TH PCREPATTERN 3 "08 October 2013" "PCRE 8.34"
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .SH "PCRE REGULAR EXPRESSION DETAILS"  .SH "PCRE REGULAR EXPRESSION DETAILS"
# Line 359  specifies two binary zeros followed by a Line 359  specifies two binary zeros followed by a
359  sure you supply two digits after the initial zero if the pattern character that  sure you supply two digits after the initial zero if the pattern character that
360  follows is itself an octal digit.  follows is itself an octal digit.
361  .P  .P
362  The handling of a backslash followed by a digit other than 0 is complicated.  The handling of a backslash followed by a digit other than 0 is complicated,
363  Outside a character class, PCRE reads it and any following digits as a decimal  and Perl has changed in recent releases, causing PCRE also to change. Outside a
364  number. If the number is less than 10, or if there have been at least that many  character class, PCRE reads the digit and any following digits as a decimal
365    number. If the number is less than 8, or if there have been at least that many
366  previous capturing left parentheses in the expression, the entire sequence is  previous capturing left parentheses in the expression, the entire sequence is
367  taken as a \fIback reference\fP. A description of how this works is given  taken as a \fIback reference\fP. A description of how this works is given
368  .\" HTML <a href="#backreferences">  .\" HTML <a href="#backreferences">
# Line 374  following the discussion of Line 375  following the discussion of
375  parenthesized subpatterns.  parenthesized subpatterns.
376  .\"  .\"
377  .P  .P
378  Inside a character class, or if the decimal number is greater than 9 and there  Inside a character class, or if the decimal number following \e is greater than
379  have not been that many capturing subpatterns, PCRE re-reads up to three octal  7 and there have not been that many capturing subpatterns, PCRE handles \e8 and
380  digits following the backslash, and uses them to generate a data character. Any  \e9 as the literal characters "8" and "9", and otherwise re-reads up to three
381  subsequent digits stand for themselves. The value of the character is  octal digits following the backslash, using them to generate a data character.
382  constrained in the same way as characters specified in hexadecimal.  Any subsequent digits stand for themselves. The value of the character is
383  For example:  constrained in the same way as characters specified in hexadecimal. For
384    example:
385  .sp  .sp
386    \e040   is another way of writing an ASCII space    \e040   is another way of writing an ASCII space
387  .\" JOIN  .\" JOIN
# Line 398  For example: Line 400  For example:
400    \e377   might be a back reference, otherwise    \e377   might be a back reference, otherwise
401              the value 255 (decimal)              the value 255 (decimal)
402  .\" JOIN  .\" JOIN
403    \e81    is either a back reference, or a binary zero    \e81    is either a back reference, or the two
404              followed by the two characters "8" and "1"              characters "8" and "1"
405  .sp  .sp
406  Note that octal values of 100 or greater must not be introduced by a leading  Note that octal values of 100 or greater must not be introduced by a leading
407  zero, because no more than three octal digits are ever read.  zero, because no more than three octal digits are ever read.
# Line 3156  Cambridge CB2 3QH, England. Line 3158  Cambridge CB2 3QH, England.
3158  .rs  .rs
3159  .sp  .sp
3160  .nf  .nf
3161  Last updated: 05 October 2013  Last updated: 08 October 2013
3162  Copyright (c) 1997-2013 University of Cambridge.  Copyright (c) 1997-2013 University of Cambridge.
3163  .fi  .fi

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