Since patterns are processed as double quoted strings, the following
also work:
- \t tab
- \n newline
- \r return
- \f form feed
- \a alarm (bell)
- \e escape (think troff)
+ \t tab (HT, TAB)
+ \n newline (LF, NL)
+ \r return (CR)
+ \f form feed (FF)
+ \a alarm (bell) (BEL)
+ \e escape (think troff) (ESC)
\033 octal char (think of a PDP-11)
\x1B hex char
\c[ control char
boundary. To match the actual end of the string, not ignoring newline,
you can use C<\Z(?!\n)>.
-When the bracketing construct C<( ... )> is used, \<digit> matches the
+When the bracketing construct C<( ... )> is used, \E<lt>digitE<gt> matches the
digit'th substring. Outside of the pattern, always use "$" instead of "\"
-in front of the digit. (While the \<digit> notation can on rare occasion work
+in front of the digit. (While the \E<lt>digitE<gt> notation can on rare occasion work
outside the current pattern, this should not be relied upon. See the
-WARNING below.) The scope of $<digit> (and C<$`>, C<$&>, and C<$'>)
+WARNING below.) The scope of $E<lt>digitE<gt> (and C<$`>, C<$&>, and C<$'>)
extends to the end of the enclosing BLOCK or eval string, or to the next
successful pattern match, whichever comes first. If you want to use
parentheses to delimit a subpattern (e.g. a set of alternatives) without
-saving it as a subpattern, follow the ( with a ?.
+saving it as a subpattern, follow the ( with a ?:.
You may have as many parentheses as you wish. If you have more
than 9 substrings, the variables $10, $11, ... refer to the
on. (\1 through \9 are always backreferences.)
C<$+> returns whatever the last bracket match matched. C<$&> returns the
-entire matched string. ($0 used to return the same thing, but not any
+entire matched string. (C<$0> used to return the same thing, but not any
more.) C<$`> returns everything before the matched string. C<$'> returns
everything after the matched string. Examples:
You will note that all backslashed metacharacters in Perl are
alphanumeric, such as C<\b>, C<\w>, C<\n>. Unlike some other regular expression
languages, there are no backslashed symbols that aren't alphanumeric.
-So anything that looks like \\, \(, \), \<, \>, \{, or \} is always
+So anything that looks like \\, \(, \), \E<lt>, \E<gt>, \{, or \} is always
interpreted as a literal character, not a metacharacter. This makes it
simple to quote a string that you want to use for a pattern but that
you are afraid might contain metacharacters. Simply quote all the
=item (?:regexp)
-This groups things like "()" but doesn't make backrefences like "()" does. So
+This groups things like "()" but doesn't make backreferences like "()" does. So
split(/\b(?:a|b|c)\b/)
"bar" that is preceded by something which is not "foo". That's because
the C<(?!foo)> is just saying that the next thing cannot be "foo"--and
it's not, it's a "bar", so "foobar" will match. You would have to do
-something like C</(?foo)...bar/> for that. We say "like" because there's
+something like C</(?!foo)...bar/> for that. We say "like" because there's
the case of your "bar" not having three characters before it. You could
cover that this way: C</(?:(?!foo)...|^..?)bar/>. Sometimes it's still
easier just to say:
whole string. As C<\d*> can match on an empty string the complete
regular expression matched successfully.
- Beginning is <I have 2: 53147>, number is <>.
+ Beginning is <I have 2 numbers: 53147>, number is <>.
Here are some variants, most of which don't work:
used in C: "\n" matches a newline, "\t" a tab, "\r" a carriage return,
"\f" a form feed, etc. More generally, \I<nnn>, where I<nnn> is a string
of octal digits, matches the character whose ASCII value is I<nnn>.
-Similarly, \xI<nn>, where I<nn> are hexidecimal digits, matches the
+Similarly, \xI<nn>, where I<nn> are hexadecimal digits, matches the
character whose ASCII value is I<nn>. The expression \cI<x> matches the
ASCII character control-I<x>. Finally, the "." metacharacter matches any
character except "\n" (unless you use C</s>).
projects / p5sagit/p5-mst-13.2.git / blobdiff