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perlcheat

Perl 5 version 12.2 documentation
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perlcheat

NAME

perlcheat - Perl 5 Cheat Sheet

DESCRIPTION

This 'cheat sheet' is a handy reference, meant for beginning Perl programmers. Not everything is mentioned, but 195 features may already be overwhelming.

The sheet

  1.   CONTEXTS  SIGILS             ARRAYS        HASHES
  2.   void      $scalar   whole:   @array        %hash
  3.   scalar    @array    slice:   @array[0, 2]  @hash{'a', 'b'}
  4.   list      %hash     element: $array[0]     $hash{'a'}
  5.             &sub
  6.             *glob    SCALAR VALUES
  7.                      number, string, reference, glob, undef
  8.   REFERENCES
  9.   \     references      $$foo[1]       aka $foo->[1]
  10.   $@%&* dereference     $$foo{bar}     aka $foo->{bar}
  11.   []    anon. arrayref  ${$$foo[1]}[2] aka $foo->[1]->[2]
  12.   {}    anon. hashref   ${$$foo[1]}[2] aka $foo->[1][2]
  13.   \()   list of refs
  14.                           NUMBERS vs STRINGS  LINKS
  15.   OPERATOR PRECEDENCE     =          =        perl.plover.com
  16.   ->                      +          .        search.cpan.org
  17.   ++ --                   == !=      eq ne         cpan.org
  18.   **                      < > <= >=  lt gt le ge   pm.org
  19.   ! ~ \ u+ u-             <=>        cmp           tpj.com
  20.   =~ !~                                            perldoc.com
  21.   * / % x                 SYNTAX
  22.   + - .                   for    (LIST) { }, for (a;b;c) { }
  23.   << >>                   while  ( ) { }, until ( ) { }
  24.   named uops              if     ( ) { } elsif ( ) { } else { }
  25.   < > <= >= lt gt le ge   unless ( ) { } elsif ( ) { } else { }
  26.   == != <=> eq ne cmp ~~  for equals foreach (ALWAYS)
  27.   &
  28.   | ^              REGEX METACHARS            REGEX MODIFIERS
  29.   &&               ^     string begin         /i case insens.
  30.   || //            $     str. end (before \n) /m line based ^$
  31.   .. ...           +     one or more          /s . includes \n
  32.   ?:               *     zero or more         /x ign. wh.space
  33.   = += -= *= etc.  ?     zero or one          /g global
  34.   , =>             {3,7} repeat in range      /o cmpl pat. once
  35.   list ops         ()    capture
  36.   not              (?:)  no capture       REGEX CHARCLASSES
  37.   and              []    character class  .  == [^\n]
  38.   or xor           |     alternation      \s == whitespace
  39.                    \b    word boundary    \w == word characters
  40.                    \z    string end       \d == digits
  41.   DO                                      \S, \W and \D negate
  42.   use strict;        DON'T
  43.   use warnings;      "$foo"           LINKS
  44.   my $var;           $$variable_name  perl.com
  45.   open() or die $!;  `$userinput`     use.perl.org
  46.   use Modules;       /$userinput/     perl.apache.org
  48.   FUNCTION RETURN LISTS
  49.   stat      localtime    caller         SPECIAL VARIABLES
  50.    0 dev    0 second     0 package      $_    default variable
  51.    1 ino    1 minute     1 filename     $0    program name
  52.    2 mode   2 hour       2 line         $/    input separator
  53.    3 nlink  3 day        3 subroutine   $\    output separator
  54.    4 uid    4 month-1    4 hasargs      $|    autoflush
  55.    5 gid    5 year-1900  5 wantarray    $!    sys/libcall error
  56.    6 rdev   6 weekday    6 evaltext     $@    eval error
  57.    7 size   7 yearday    7 is_require   $$    process ID
  58.    8 atime  8 is_dst     8 hints        $.    line number
  59.    9 mtime               9 bitmask      @ARGV command line args
  60.   10 ctime  just use                    @INC  include paths
  61.   11 blksz  POSIX::      3..9 only      @_    subroutine args
  62.   12 blcks  strftime!    with EXPR      %ENV  environment

ACKNOWLEDGEMENTS

The first version of this document appeared on Perl Monks, where several people had useful suggestions. Thank you, Perl Monks.

A special thanks to Damian Conway, who didn't only suggest important changes, but also took the time to count the number of listed features and make a Perl 6 version to show that Perl will stay Perl.

AUTHOR

Juerd Waalboer <#####@juerd.nl>, with the help of many Perl Monks.

SEE ALSO

  1.  http://perlmonks.org/?node_id=216602      the original PM post
  2.  http://perlmonks.org/?node_id=238031      Damian Conway's Perl 6 version
  3.  http://juerd.nl/site.plp/perlcheat        home of the Perl Cheat Sheet
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