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<HTML><HEAD><TITLE>Recipe 6.23. Regular Expression Grabbag (Perl Cookbook)</TITLE><METANAME="DC.title"CONTENT="Perl Cookbook"><METANAME="DC.creator"CONTENT="Tom Christiansen & Nathan Torkington"><METANAME="DC.publisher"CONTENT="O'Reilly & Associates, Inc."><METANAME="DC.date"CONTENT="1999-07-02T01:35:12Z"><METANAME="DC.type"CONTENT="Text.Monograph"><METANAME="DC.format"CONTENT="text/html"SCHEME="MIME"><METANAME="DC.source"CONTENT="1-56592-243-3"SCHEME="ISBN"><METANAME="DC.language"CONTENT="en-US"><METANAME="generator"CONTENT="Jade 1.1/O'Reilly DocBook 3.0 to HTML 4.0"><LINKREV="made"HREF="mailto:online-books@oreilly.com"TITLE="Online Books Comments"><LINKREL="up"HREF="ch06_01.htm"TITLE="6. Pattern Matching"><LINKREL="prev"HREF="ch06_23.htm"TITLE="6.22. Program: tcgrep"><LINKREL="next"HREF="ch07_01.htm"TITLE="7. File Access"></HEAD><BODYBGCOLOR="#FFFFFF"><img alt="Book Home" border="0" src="gifs/smbanner.gif" usemap="#banner-map" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Perl Cookbook"><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><p><TABLEWIDTH="684"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch06_23.htm"TITLE="6.22. Program: tcgrep"><IMGSRC="../gifs/txtpreva.gif"ALT="Previous: 6.22. Program: tcgrep"BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="228"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1"><ACLASS="chapter"REL="up"HREF="ch06_01.htm"TITLE="6. Pattern Matching"></A></FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="228"><ACLASS="chapter"HREF="ch07_01.htm"TITLE="7. File Access"><IMGSRC="../gifs/txtnexta.gif"ALT="Next: 7. File Access"BORDER="0"></A></TD></TR></TABLE></DIV><DIVCLASS="sect1"><H2CLASS="sect1"><ACLASS="title"NAME="ch06-33146">6.23. Regular Expression Grabbag</A></H2><PCLASS="para">We have found these <ACLASS="indexterm"NAME="ch06-idx-1000007741-0"></A><ACLASS="indexterm"NAME="ch06-idx-1000007741-1"></A>regular expressions useful or interesting.</P><DLCLASS="variablelist"><DTCLASS="term">Roman numbers </DT><DDCLASS="listitem"><PRECLASS="programlisting">m/^m*(d?c{0,3}|c[dm])(l?x{0,3}|x[lc])(v?i{0,3}|i[vx])$/i</PRE></DD><DTCLASS="term">Swap first two words </DT><DDCLASS="listitem"><PRECLASS="programlisting">s/(\S+)(\s+)(\S+)/$3$2$1/</PRE></DD><DTCLASS="term">Keyword = Value </DT><DDCLASS="listitem"><PRECLASS="programlisting">m/(\w+)\s*=\s*(.*)\s*$/ # keyword is $1, value is $2</PRE></DD><DTCLASS="term">Line of at least 80 characters </DT><DDCLASS="listitem"><PRECLASS="programlisting">m/.{80,}/</PRE></DD><DTCLASS="term">MM/DD/YY HH:MM:SS </DT><DDCLASS="listitem"><PRECLASS="programlisting">m|(\d+)/(\d+)/(\d+) (\d+):(\d+):(\d+)|</PRE></DD><DTCLASS="term">Changing directories </DT><DDCLASS="listitem"><PRECLASS="programlisting">s(/usr/bin)(/usr/local/bin)g</PRE></DD><DTCLASS="term">Expanding %7E (hex) escapes </DT><DDCLASS="listitem"><PRECLASS="programlisting">s/%([0-9A-Fa-f][0-9A-Fa-f])/chr hex $1/ge</PRE></DD><DTCLASS="term">Deleting C comments (imperfectly) </DT><DDCLASS="listitem"><PRECLASS="programlisting">s{ /\* # Match the opening delimiter .*? # Match a minimal number of characters \*/ # Match the closing delimiter} []gsx;</PRE></DD><DTCLASS="term">Removing leading and trailing whitespace </DT><DDCLASS="listitem"><PRECLASS="programlisting">s/^\s+//;s/\s+$//;</PRE></DD><DTCLASS="term">Turning \ followed by n into a real newline </DT><DDCLASS="listitem"><PRECLASS="programlisting">s/\\n/\n/g;</PRE></DD><DTCLASS="term">Removing package portion of fully qualified symbols </DT><DDCLASS="listitem"><PRECLASS="programlisting">s/^.*:://</PRE></DD><DTCLASS="term">IP address </DT><DDCLASS="listitem"><PRECLASS="programlisting">m/^([01]?\d\d|2[0-4]\d|25[0-5])\.([01]?\d\d|2[0-4]\d|25[0-5])\. ([01]?\d\d|2[0-4]\d|25[0-5])\.([01]?\d\d|2[0-4]\d|25[0-5])$/;</PRE></DD><DTCLASS="term">Removing leading path from filename </DT><DDCLASS="listitem"><PRECLASS="programlisting">s(^.*/)()</PRE></DD><DTCLASS="term">Extracting columns setting from TERMCAP </DT><DDCLASS="listitem"><PRECLASS="programlisting">$cols = ( ($ENV{TERMCAP} || " ") =~ m/:co#(\d+):/ ) ? $1 : 80;</PRE></DD><DTCLASS="term">Removing directory components from program name and arguments </DT><DDCLASS="listitem"><PRECLASS="programlisting">($name = " $0 @ARGV") =~ s, /\S+/, ,g;</PRE></DD><DTCLASS="term">Checking your operating system </DT><DDCLASS="listitem"><PRECLASS="programlisting">die "This isn't Linux" unless $^O =~ m/linux/i;</PRE></DD><DTCLASS="term">Joining continuation lines in multiline string </DT><DDCLASS="listitem"><PRECLASS="programlisting">s/\n\s+/ /g</PRE></DD><DTCLASS="term">Extracting all numbers from a string </DT><DDCLASS="listitem"><PRECLASS="programlisting">@nums = m/(\d+\.?\d*|\.\d+)/g;</PRE></DD><DTCLASS="term">Finding all-caps words </DT><DDCLASS="listitem"><PRECLASS="programlisting">@capwords = m/(\b[^\Wa-z0-9_]+\b)/g;</PRE></DD><DTCLASS="term">Finding all-lowercase words </DT><DDCLASS="listitem"><PRECLASS="programlisting">@lowords = m/(\b[^\WA-Z0-9_]+\b)/g;</PRE></DD><DTCLASS="term">Finding initial-caps word </DT><DDCLASS="listitem"><PRECLASS="programlisting">@icwords = m/(\b[^\Wa-z0-9_][^\WA-Z0-9_]*\b)/;</PRE></DD><DTCLASS="term">Finding links in simple HTML </DT><DDCLASS="listitem"><PRECLASS="programlisting">@links = m/<A[^>]+?HREF\s*=\s*["']?([^'" >]+?)[ '"]?>/sig;</PRE></DD><DTCLASS="term">Finding middle initial in $_ </DT><DDCLASS="listitem"><PRECLASS="programlisting">($initial) = m/^\S+\s+(\S)\S*\s+\S/ ? $1 : "";</PRE></DD><DTCLASS="term">Changing inch marks to quotes </DT><DDCLASS="listitem"><PRECLASS="programlisting">s/"([^"]*)"/``$1''/g</PRE></DD><DTCLASS="term">Extracting sentences (two spaces required) </DT><DDCLASS="listitem"><PRECLASS="programlisting">{ local $/ = ""; while (<>) { s/\n/ /g; s/ {3,}/ /g; push @sentences, m/(\S.*?[!?.])(?= |\Z)/g; }}</PRE></DD><DTCLASS="term">YYYY-MM-DD </DT><DDCLASS="listitem"><PRECLASS="programlisting">m/(\d{4})-(\d\d)-(\d\d)/ # YYYY in $1, MM in $2, DD in $3</PRE></DD><DTCLASS="term">North American telephone numbers </DT><DDCLASS="listitem"><PRECLASS="programlisting">m/ ^ (?: 1 \s (?: \d\d\d \s)? # 1, or 1 and area code | # ... or ... \(\d\d\d\) \s # area code with parens | # ... or ... (?: \+\d\d?\d? \s)? # optional +country code \d\d\d ([\s\-]) # and area code ) \d\d\d (\s|\1) # prefix (and area code separator) \d\d\d\d # exchange $ /x</PRE></DD><DTCLASS="term">Exclamations </DT><DDCLASS="listitem"><PRECLASS="programlisting">m/\boh\s+my\s+gh?o(d(dess(es)?|s?)|odness|sh)\b/i</PRE></DD><DTCLASS="term">Extracting lines regardless of line terminator </DT><DDCLASS="listitem"><PRECLASS="programlisting">push(@lines, $1) while ($input =~ s/^([^\012\015]*)(\012\015?|\015\012?)//);<ACLASS="indexterm"NAME="ch06-idx-1000007753-0"></A><ACLASS="indexterm"NAME="ch06-idx-1000007753-1"></A><ACLASS="indexterm"NAME="ch06-idx-1000007753-2"></A></PRE></DD></DL></DIV><DIVCLASS="htmlnav"><P></P><HRALIGN="LEFT"WIDTH="684"TITLE="footer"><TABLEWIDTH="684"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch06_23.htm"TITLE="6.22. Program: tcgrep"><IMGSRC="../gifs/txtpreva.gif"ALT="Previous: 6.22. 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