PERLCHEAT(1) Perl Programmers Reference Guide PERLCHEAT(1) #

PERLCHEAT(1) Perl Programmers Reference Guide PERLCHEAT(1)

NNAAMMEE #

 perlcheat - Perl 5 Cheat Sheet

DDEESSCCRRIIPPTTIIOONN #

 This 'cheat sheet' is a handy reference, meant for beginning Perl
 programmers. Not everything is mentioned, but 195 features may already be
 overwhelming.

TThhee sshheeeett 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

SYNTAX #

   OPERATOR PRECEDENCE    foreach (LIST) { }     for (a;b;c) { }
   ->                     while   (e) { }        until (e)   { }
   ++ --                  if      (e) { } elsif (e) { } else { }
   **                     unless  (e) { } elsif (e) { } else { }
   ! ~ \ u+ u-            given   (e) { when (e) {} default {} }
   =~ !~
   * / % x                 NUMBERS vs STRINGS  FALSE vs TRUE
   + - .                   =          =        undef, "", 0, "0"
   << >>                   +          .        anything else
   named uops              == !=      eq ne
   < > <= >= lt gt le ge   < > <= >=  lt gt le ge
   == != <=> eq ne cmp ~~  <=>        cmp
   &

| ^ REGEX MODIFIERS REGEX METACHARS #

   &&              /i case insensitive   ^      string begin
   || //           /m line based ^$      $      str end (bfr \n)
   .. ...          /s . includes \n      +      one or more
   ?:              /x /xx ign. wh.space  *      zero or more
   = += last goto  /p preserve           ?      zero or one
   , =>            /a ASCII    /aa safe  {3,7}  repeat in range
   list ops        /l locale   /d  dual  |      alternation
   not             /u Unicode            []     character class
   and             /e evaluate /ee rpts  \b     boundary
   or xor          /g global             \z     string end
                   /o compile pat once   ()     capture
   DEBUG                                 (?:p)  no capture
   -MO=Deparse     REGEX CHARCLASSES     (?#t)  comment
   -MO=Terse       .   [^\n]             (?=p)  ZW pos ahead
   -D##            \s  whitespace        (?!p)  ZW neg ahead
   -d:Trace        \w  word chars        (?<=p) ZW pos behind \K
                   \d  digits            (?<!p) ZW neg behind
   CONFIGURATION   \pP named property    (?>p)  no backtrack
   perl -V:ivsize  \h  horiz.wh.space    (?|p|p)branch reset
                   \R  linebreak         (?<n>p)named capture
                   \S \W \D \H negate    \g{n}  ref to named cap
                                         \K     keep left part

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

AACCKKNNOOWWLLEEDDGGEEMMEENNTTSS #

 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 Raku version to show that Perl will stay Perl.

AAUUTTHHOORR #

 Juerd Waalboer <#####@juerd.nl>, with the help of many Perl Monks.

SSEEEE AALLSSOO #

 •   <https://perlmonks.org/?node_id=216602> - the original PM post

 •   <https://perlmonks.org/?node_id=238031> - Damian Conway's Raku
     version

 •   <https://juerd.nl/site.plp/perlcheat> - home of the Perl Cheat Sheet

perl v5.36.3 2021-03-02 PERLCHEAT(1)