149 lines
4.8 KiB
Perl
149 lines
4.8 KiB
Perl
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#Character Class: Alternative Characters!
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Metacharacter What It Matches
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was|were|will Matches one of was, were, or will
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#Character Class: Anchored Characters!
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Metacharacter What It Matches
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\b Matches a word boundary (when not inside [ ])
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\B Matches a nonword boundary
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^ Matches to beginning of line
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$ Matches to end of line
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\A Matches the beginning of the string only
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\Z Matches the end of the string or line
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\z Matches the end of string only
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\G Matches where previous m//g left off
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#Character Class: Miscellaneous Characters!
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Metacharacter What It Matches
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\12 Matches that octal value, up to \377
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\x811 Matches that hex value
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\cX Matches that control character; e.g., \cC is <Ctrl>-C and \cV is <Ctrl>-V
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\e Matches the ASCII ESC character, not backslash
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\E Marks the end of changing case with \U, \L, or \Q
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\l Lowercase the next character only
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\L Lowercase characters until the end of the string or until \E
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\N Matches that named character; e.g., \N{greek:Beta}
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\p{PROPERTY} Matches any character with the named property; e.g., \p{IsAlpha}/
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\P{PROPERTY} Matches any character without the named property
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\Q Quote metacharacters until \E
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\u Titlecase next character only
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\U Uppercase until \E
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\x{NUMBER} Matches Unicode NUMBER given in hexadecimal
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\X Matches Unicode "combining character sequence" string
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\[ Matches that metacharacter
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\\ Matches a backslash
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#Character Class: Remembered Characters!
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Metacharacter What It Matches
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(string) Used for backreferencing (see Examples 9.38 and 9.39)
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\1 or $1 Matches first set of parentheses[a]
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\2 or $2 Matches second set of parentheses
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\3 or $3 Matches third set of parenthes
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#Character Class: Repeated Characters!
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Metacharacter What It Matches
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x? Matches 0 or 1 x
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x* Matches 0 or more occurrences of x
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x+ Matches 1 or more occurrences of x
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(xyz)+ Matches 1 or more patterns of xyz
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x{m,n} Matches at least m occurrences of x and no more than n occurrences of x
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#Character Class: Whitespace Characters!
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Metacharacter What It Matches
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\s Matches a whitespace character, such as spaces, tabs, and newlines
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\S Matches nonwhitespace character
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\n Matches a newline
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\r Matches a return
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\t Matches a tab
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\f Matches a form feed
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\b Matches a backspace
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\0 Matches a null character
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#Match any number of alphanumerics followed by a single space character!
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$p = "This is a pattern test.";
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if ($p =~ /(\w*\s)/){ print "$1\n"; }
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#Match at least one alphanumeric followed by a single space character!
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if ($p =~ /(\w+\s)/){ print "$1\n"; }
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#Posix and Unicode Classes!
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Shortcut Expansion Description
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[[:alpha:]] [a-zA-Z] An alphabetic character.
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[[:alnum:]] [0-9A-Za-z] An alphabetic or numeric character.
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[[:digit:]] \d A digit, 0-9.
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[[:lower:]] [a-z] A lower case letter.
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[[:upper:]] [A-Z] An upper case letter.
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[[:punct:]] [!"#$%&'()*+,-./:;<=>?@\[\\\]^_`{|}~] A punctuation character note the escaped characters [, \, and ].
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/bea?t/ Matches either 'beat' or 'bet'
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/bea+t/ Matches 'beat', 'beaat', 'beaaat'
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/bea*t/ Matches 'bet', 'beat', 'beaat'
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#The bracket metacharacters and negation!
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while(<DATA>){
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print if / [^123]0/
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}
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__DATA__
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101
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201
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301
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401
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501
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601
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