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Re^4: Passing variables into regular expressions

by johngg (Canon)
on Apr 20, 2006 at 14:08 UTC ( #544605=note: print w/replies, xml ) Need Help??

in reply to Re^3: Passing variables into regular expressions
in thread Passing variables into regular expressions

Looking at the Camel book, 3rd edn., table 5-1 on page 150, the entry for /s says "Let . match newline ... " which sort of implies that /m doesn't. So it is the treatment of the "." metacharacter that changes between the two. This with no modifying flag also matches

($span_d) = $str =~ /(\d\d\w+\s\w+\d\d/;

This might imply that the default behaviour of m/.../ with no modifying flag is the same as m/.../m. I will delve into the documentation when I get a chance.




This passage is in the "perlre" manual page

... m Treat string as multiple lines. That is, change "^" and "$" from matching the start or end of the string to matching the start or end of any line anywhere within the string. s Treat string as single line. That is, change "." to match any character whatsoever, even a newline, which normally it would not match. The "/s" and "/m" modifiers both override the $* setting. That is, no matter what $* contains, "/s" without "/m" will force "^" to match only at the beginning of the string and "$" to match only at the end (or just before a newline at the end) of the string. Together, as /ms, they let the "." match any character whatsoever, while still allowing "^" and "$" to match, respectively, just after and just before newlines within the string. ... perl v5.8.4 Last change: 2004-01-17 1

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