Hello,
I am wondering on some metacharacters in regular expressions.
According to Wall et al. (2000, p. 158), there are 12 metacharacters:
* + ? . \ | ( ) [ { ^ $
On the other hand, the Perl regular expressions quick start (http://perldoc.perl.org/perlrequick.html
) cites 14 metacharacters: {}[]()^$.|*+?\
First, I am not quite sure about the status of } and ]. Can somebody
explain the discrepancy between the two sources?
In addition, { and } seem to be fully acceptable characters outside an
expression like {MIN, MAX} and patterns m/{my string}/ or m/{my
string/ do not raise any exception or error. This is not the case for
( and the instruction m/(my string/ stops the program with an
"unmatched" message. My question is: What are the different escape
treatments for the different metacharacters?
A simple solution for a programmer that would like to ignore this
would be to quote every purported metacharacter, when it appears as a
literal; but I would like to understand how the algorithm really
works... Do you know where I could find a clarification on that?
Thank you in advance.
Pierre
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