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perlcheat

Perl 5 version 16.2 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  ref        ARRAYS        HASHES
  2.   void      $scalar SCALAR     @array        %hash
  3.   scalar    @array  ARRAY      @array[0, 2]  @hash{'a', 'b'}
  4.   list      %hash   HASH       $array[0]     $hash{'a'}
  5.             &sub    CODE
  6.             *glob   GLOB       SCALAR VALUES
  7.                     FORMAT     number, string, ref, glob, undef
  8.   REFERENCES
  9.   \      reference       $$foo[1]       aka $foo->[1]
  10.   $@%&*  dereference     $$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    =          =          perldoc.perl.org
  16.   ->                     +          .           search.cpan.org
  17.   ++ --                  == !=      eq ne              cpan.org
  18.   **                     < > <= >=  lt gt le ge          pm.org
  19.   ! ~ \ u+ u-            <=>        cmp                p3rl.org
  20.   =~ !~                                           perlmonks.org
  21.   * / % x                SYNTAX
  22.     + - .                  foreach (LIST) { }     for (a;b;c) { }
  23.     << >>                  while   (e) { }        until (e)   { }
  24.     named uops             if      (e) { } elsif (e) { } else { }
  25.     < > <= >= lt gt le ge  unless  (e) { } elsif (e) { } else { }
  26.     == != <=> eq ne cmp ~~ given   (e) { when (e) {} default {} }
  27.     &
  28.     | ^             REGEX METACHARS          REGEX MODIFIERS
  29.     &&              ^      string begin      /i case insensitive
  30.   || //           $      str end (bfr \n)  /m line based ^$
  31.     .. ...          +      one or more       /s . includes \n
  32.   ?:              *      zero or more      /x ignore wh.space
  33.   = += -= *= etc  ?      zero or one       /p preserve
  34.   , =>            {3,7}  repeat in range   /a ASCII    /aa safe
  35.   list ops        |      alternation       /l locale   /d  dual
  36.   not             []     character class   /u Unicode
  37.   and             \b     word boundary     /e evaluate /ee rpts
  38.   or xor          \z     string end        /g global
  39.                   ()     capture           /o compile pat once
  40.   DEBUG           (?:p)  no capture
  41.       -MO=Deparse    (?#t)  comment           REGEX CHARCLASSES
  42.    -MO=Terse      (?=p)  ZW pos ahead      .   [^\n]
  43.       -D##           (?!p)  ZW neg ahead      \s  whitespace
  44.       -d:Trace       (?<=p) ZW pos behind \K  \w  word chars
  45.                                     (?<!p) ZW neg behind     \d  digits
  46.     CONFIGURATION   (?>p)  no backtrack      \pP named property
  47.     perl -V:ivsize  (?|p|p)branch reset      \h  horiz.wh.space
  48.                   (?&NM) cap to name       \R  linebreak
  49.                                                                                       \S \W \D \H negate
  50.     FUNCTION RETURN LISTS
  51.     stat      localtime    caller         SPECIAL VARIABLES
  52.       0 dev    0 second      0 package     $_    default variable
  53.       1 ino    1 minute      1 filename    $0    program name
  54.       2 mode   2 hour        2 line        $/    input separator
  55.       3 nlink  3 day         3 subroutine  $\    output separator
  56.       4 uid    4 month-1     4 hasargs     $|    autoflush
  57.       5 gid    5 year-1900   5 wantarray   $!    sys/libcall error
  58.       6 rdev   6 weekday     6 evaltext    $@    eval error
  59.       7 size   7 yearday     7 is_require  $$    process ID
  60.       8 atime  8 is_dst      8 hints       $.    line number
  61.       9 mtime                9 bitmask     @ARGV command line args
  62.     10 ctime               10 hinthash    @INC  include paths
  63.     11 blksz               3..10 only     @_    subroutine args
  64.     12 blcks               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

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