- 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