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# perlcheat

Perl 5 version 16.0 documentation
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# perlcheat

- NAME
- DESCRIPTION
  - The sheet
- ACKNOWLEDGEMENTS
- AUTHOR
- SEE ALSO

# 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

      CONTEXTS  SIGILS  ref        ARRAYS        HASHES  void      $scalar SCALAR     @array        %hash  scalar    @array  ARRAY      @array[0, 2]  @hash{'a', 'b'}  list      %hash   HASH       $array[0]     $hash{'a'}            &sub    CODE            *glob   GLOB       SCALAR VALUES                    FORMAT     number, string, ref, glob, undef  REFERENCES  \      reference       $$foo[1]       aka $foo->[1]  $@%&*  dereference     $$foo{bar}     aka $foo->{bar}  []     anon. arrayref  ${$$foo[1]}[2] aka $foo->[1]->[2]  {}     anon. hashref   ${$$foo[1]}[2] aka $foo->[1][2]  \()    list of refs                         NUMBERS vs STRINGS    LINKS  OPERATOR PRECEDENCE    =          =          perldoc.perl.org  ->                     +          .           search.cpan.org  ++ --                  == !=      eq ne              cpan.org  **                     < > <= >=  lt gt le ge          pm.org  ! ~ \ u+ u-            <=>        cmp                p3rl.org  =~ !~                                           perlmonks.org  * / % x                SYNTAX    + - .                  foreach (LIST) { }     for (a;b;c) { }    << >>                  while   (e) { }        until (e)   { }    named uops             if      (e) { } elsif (e) { } else { }    < > <= >= lt gt le ge  unless  (e) { } elsif (e) { } else { }    == != <=> eq ne cmp ~~ given   (e) { when (e) {} default {} }    &    | ^             REGEX METACHARS          REGEX MODIFIERS    &&              ^      string begin      /i case insensitive  || //           $      str end (bfr \n)  /m line based ^$    .. ...          +      one or more       /s . includes \n  ?:              *      zero or more      /x ignore wh.space  = += -= *= etc  ?      zero or one       /p preserve  , =>            {3,7}  repeat in range   /a ASCII    /aa safe  list ops        |      alternation       /l locale   /d  dual  not             []     character class   /u Unicode  and             \b     word boundary     /e evaluate /ee rpts  or xor          \z     string end        /g global                  ()     capture           /o compile pat once  DEBUG           (?:p)  no capture      -MO=Deparse    (?#t)  comment           REGEX CHARCLASSES   -MO=Terse      (?=p)  ZW pos ahead      .   [^\n]      -D##           (?!p)  ZW neg ahead      \s  whitespace      -d:Trace       (?<=p) ZW pos behind \K  \w  word chars                                    (?<!p) ZW neg behind     \d  digits    CONFIGURATION   (?>p)  no backtrack      \pP named property    perl -V:ivsize  (?|p|p)branch reset      \h  horiz.wh.space                  (?&NM) cap to name       \R  linebreak                                                                                      \S \W \D \H negate    FUNCTION RETURN LISTS    stat      localtime    caller         SPECIAL VARIABLES      0 dev    0 second      0 package     $_    default variable      1 ino    1 minute      1 filename    $0    program name      2 mode   2 hour        2 line        $/    input separator      3 nlink  3 day         3 subroutine  $\    output separator      4 uid    4 month-1     4 hasargs     $|    autoflush      5 gid    5 year-1900   5 wantarray   $!    sys/libcall error      6 rdev   6 weekday     6 evaltext    $@    eval error      7 size   7 yearday     7 is_require  $$    process ID      8 atime  8 is_dst      8 hints       $.    line number      9 mtime                9 bitmask     @ARGV command line args    10 ctime               10 hinthash    @INC  include paths    11 blksz               3..10 only     @_    subroutine args    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

- http://perlmonks.org/?node_id=216602 - the original PM post

- http://perlmonks.org/?node_id=238031 - Damian Conway's Perl 6 version

- http://juerd.nl/site.plp/perlcheat - home of the Perl Cheat Sheet

Page index

- NAME
- DESCRIPTION
  - The sheet
- ACKNOWLEDGEMENTS
- AUTHOR
- SEE ALSO