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   1  =head1 NAME
   2  
   3  perlcheat - Perl 5 Cheat Sheet
   4  
   5  =head1 DESCRIPTION
   6  
   7  This 'cheat sheet' is a handy reference, meant for beginning Perl
   8  programmers. Not everything is mentioned, but 195 features may
   9  already be overwhelming.
  10  
  11  =head2 The sheet
  12  
  13    CONTEXTS  SIGILS             ARRAYS        HASHES
  14    void      $scalar   whole:   @array        %hash
  15    scalar    @array    slice:   @array[0, 2]  @hash{'a', 'b'}
  16    list      %hash     element: $array[0]     $hash{'a'}
  17              &sub
  18              *glob    SCALAR VALUES
  19                       number, string, reference, glob, undef
  20    REFERENCES
  21    \     references      $$foo[1]       aka $foo->[1]
  22    $@%&* dereference     $$foo{bar}     aka $foo->{bar}
  23    []    anon. arrayref  ${$$foo[1]}[2] aka $foo->[1]->[2]
  24    {}    anon. hashref   ${$$foo[1]}[2] aka $foo->[1][2]
  25    \()   list of refs
  26                            NUMBERS vs STRINGS  LINKS
  27    OPERATOR PRECEDENCE     =          =        perl.plover.com
  28    ->                      +          .        search.cpan.org
  29    ++ --                   == !=      eq ne         cpan.org
  30    **                      < > <= >=  lt gt le ge   pm.org
  31    ! ~ \ u+ u-             <=>        cmp           tpj.com
  32    =~ !~                                            perldoc.com
  33    * / % x                 SYNTAX
  34    + - .                   for    (LIST) { }, for (a;b;c) { }
  35    << >>                   while  ( ) { }, until ( ) { }
  36    named uops              if     ( ) { } elsif ( ) { } else { }
  37    < > <= >= lt gt le ge   unless ( ) { } elsif ( ) { } else { }
  38    == != <=> eq ne cmp     for equals foreach (ALWAYS)
  39    &
  40    | ^              REGEX METACHARS            REGEX MODIFIERS
  41    &&               ^     string begin         /i case insens.
  42    ||               $     str. end (before \n) /m line based ^$
  43    .. ...           +     one or more          /s . includes \n
  44    ?:               *     zero or more         /x ign. wh.space
  45    = += -= *= etc.  ?     zero or one          /g global
  46    , =>             {3,7} repeat in range      /o cmpl pat. once
  47    list ops         ()    capture
  48    not              (?:)  no capture       REGEX CHARCLASSES
  49    and              []    character class  .  == [^\n]
  50    or xor           |     alternation      \s == whitespace
  51                     \b    word boundary    \w == word characters
  52                     \z    string end       \d == digits
  53    DO                                      \S, \W and \D negate
  54    use strict;        DON'T
  55    use warnings;      "$foo"           LINKS
  56    my $var;           $$variable_name  perl.com
  57    open() or die $!;  `$userinput`     use.perl.org
  58    use Modules;       /$userinput/     perl.apache.org
  59  
  60    FUNCTION RETURN LISTS
  61    stat      localtime    caller         SPECIAL VARIABLES
  62     0 dev    0 second     0 package      $_    default variable
  63     1 ino    1 minute     1 filename     $0    program name
  64     2 mode   2 hour       2 line         $/    input separator
  65     3 nlink  3 day        3 subroutine   $\    output separator
  66     4 uid    4 month-1    4 hasargs      $|    autoflush
  67     5 gid    5 year-1900  5 wantarray    $!    sys/libcall error
  68     6 rdev   6 weekday    6 evaltext     $@    eval error
  69     7 size   7 yearday    7 is_require   $$    process ID
  70     8 atime  8 is_dst     8 hints        $.    line number
  71     9 mtime               9 bitmask      @ARGV command line args
  72    10 ctime  just use                    @INC  include paths
  73    11 blksz  POSIX::      3..9 only      @_    subroutine args
  74    12 blcks  strftime!    with EXPR      %ENV  environment
  75  
  76  =head1 ACKNOWLEDGEMENTS
  77  
  78  The first version of this document appeared on Perl Monks, where several
  79  people had useful suggestions. Thank you, Perl Monks.
  80  
  81  A special thanks to Damian Conway, who didn't only suggest important changes,
  82  but also took the time to count the number of listed features and make a
  83  Perl 6 version to show that Perl will stay Perl.
  84  
  85  =head1 AUTHOR
  86  
  87  Juerd Waalboer <#####@juerd.nl>, with the help of many Perl Monks.
  88  
  89  =head1 SEE ALSO
  90  
  91   http://perlmonks.org/?node_id=216602      the original PM post
  92   http://perlmonks.org/?node_id=238031      Damian Conway's Perl 6 version
  93   http://juerd.nl/site.plp/perlcheat        home of the Perl Cheat Sheet