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CONTENTS

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

init