Perl Cookbook
by Tom Christiansen & Nathan Torkington


Here are the changes made in the 12/00 reprint:


(xxviii) Knuth's "The Art of Computer Programming" now says 3rd Edition, 1998.


(37) 1st paragraph:
Reference to Recipe 16.14 (installing an output filter) was changed to Recipe 
16.5.


{71} table listing the time fuction variables:  
"1-366" now reads "0-365." 


(73) first paragraph
"YYYY-MM-DD," now reads "YYYY MM DD",


{80} 2nd program block example, first line, missing semicolon:
terminating semicolon missing in example; as shown, recipe will abort.

was:
	
	use Date:Calc qw(Day_of_Week Week_Number Day_of_Week_to_Text)
                                                             ^
now reads:

	use Date:Calc qw(Day_of_Week Week_Number Day_of_Week_to_Text);


[81]  1st code block:
The timelocal function expects months to be in a 0 based format (i.e. 0 = 
Jan).  In the example given, the date "1998-06-03" is parsed and sent as is to
timelocal().  The month value ("03") should be decremented by 1 before being 
passed to timelocal().

now reads:

     	$epoch_seconds = timelocal(0, 0, 0, $dd, $mm-1, $yyyy-1900);


{84} code now reads:
  
first chunk:
	
	use Time::HiRes;
  	$t0 = Time::HiRes::time;
  	## do your operation here
  	$t1 = Time::HiRes::time;
  	$elapsed = $t1 - $t0;
  	# $elapsed is a floating point value, representing number
  	# of seconds between $t1 and $t2

second chunk:
	
	use Time::HiRes;
  	print "Press Return when ready: ";
  	$before = Time::HiRes::time();
  	$line = <>;
  	$elapsed = Time::HiRes::time() - $before;
  	print "You took $elapsed seconds.\n";
  	Press return when ready:
  	You took 0.228149 seconds.


(126) 4th paragraph:
now reads:

	You call n2perm with two arguments: the permutation number 
	to generate (from 0 through factorial(N)-1, where N is the 
	size of your array) and the subscript of the array's last 
	element.


(165) 5th paragraph:
In the code before the "See Also" block, the first line now read

  	($a = $b) =~ s/x/y/g;		# copy $b to $a, then change $b


[172]  3rd para:
The correct text now reads:

  When you want the last match of arbitrary pattern A, you find A 
  followed by any number of characters not followed by A.
  The general construct is A(?!.*A), which can be broken up
  for legibility:

    m{
        A              # find some pattern A
        (?!            # mustn't be able to find
             .*        # something
             A         # and A
        )
     }x


{255} line 7:
     
	% cc -o fionread fionread

now reads
    
     	% cc -o fionread fionread.c


{284} last code:
    
	$data = '/usr/share/games/fortunes';

now reads
    
    	@ARGV = qw( /usr/share/games/fortunes );


{295} line 4 from bottom:
    
	... $time, $line, $time);

now reads

    	... $time, $line, $host);


{304} line 10 of middle code:
The while statement was left-shifted one tabstop.


{307} line -7: 
"sizeofor" now reads "sizeof or".


{307} line -8
"die" now reads "warn." 


(312) -2.2:
"change directory" now reads "change the directory." (Sounded too much like 
chdir as written).


(315) footnote:
"...by the owner" now reads "...by the file's owner."


(322) 1st line: 
"file;" now reads "filename;".


{330} 1.17:
07777 now reads 0777.


{330} 1.23:

	chdir $srcdir; 

now reads 

	chdir $srcdir or die "Can't chdir to $srcdir: $!";


{333}  subroutine definitions for user and group:
the line
    
     	$user{$uid} = getpwuid($uid)->name || "#$uid"

now reads
    
     	$user{$uid} = getpwuid($uid) ? getpwuid($uid)->name : "#$uid"

Likewise, the line
     
     	$group{$gid} = getgrgid($gid)->name || "#$gid"

now reads
    
     	$group{$gid} = getgrgid($gid) ? getgrgid($gid)->name : "#$gid"


{403}

	BEGIN {
 	      unless (eval "use $mod") {
 		   warn "couldn't load $mod: $@";
 	      }
       }

now reads

	BEGIN {
	eval "use $mod";
	if ($@) { warn "$@"}
	}


{430} -1.7:
	
     	FineTime.ccc
    
now reads
	
     	Finetime.c && cc
    
Also, "FineTime.c" in "FineTime.cRunning" was moved to the previous line.


(435) last code comment:
"have your own a" now reads "have your own".


[510]  "See Also" section:
This URL is out of date:

  	http://www.hermetica.com/technologia/perl/DBI/

The current location of the documents formerly found there now reads:

  	http://www.symbolstone.org/technology/perl/DBI/


[556] 5th paragraph:
"(but not backticks)" was removed. 


[617] under "Discussion" concerning UNIX Domain Datagram Server:
The variable LocalAddr was changed to Local and PeerAddr was changed to Peer. 


{618} If you want its actual host name:

	use Socket;

	$other_end        = getpeername(SOCKET)
	    or die "Couldn't identify other end: $!\n";
	($port, $iaddr)   = unpack_sockaddr_in($other_end);
	$actual_ip        = inet_ntoa($iaddr);
	$claimed_hostname = gethostbyaddr($iaddr, AF_INET);
	@name_lookup      = gethostbyname($claimed_hostname)
	    or die "Could not look up $claimed_hostname : $!\n";
	@resolved_ips     = map { inet_ntoa($_) }
	    @ips_for_hostname[ 4 .. $#ips_for_hostname ];

But look at the misconnect between the variables used in the last two lines! 
They now read:

	@name_lookup      = gethostbyname($claimed_hostname)
	    or die "Could not look up $claimed_hostname : $!\n";
	@resolved_ips     = map { inet_ntoa($_) }
	    @name_lookup[ 4 .. $#name_lookup ];


(658) 2nd paragraph:
The example coded now reads:

	$undeleted = $pop->list();
	foreach $msgnum (keys %$undeleted) {
    	    $msgsize = $undeleted->{$msgnum};
    	    print "Message $msgnum is $msgsize bytes long.\n";
	}


(716) third paragraph now reads:

  	A correct but slower and slightly more complicated way is 
	to use the HTML-Tree bundle of modules from CPAN: