Linux Certif

Toute la documentation sur la certification Linux LPI

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 194 features may already be overwhelming.

The sheet

  CONTEXTS  SIGILS             ARRAYS        HASHES

  void      $scalar   whole:   @array        %hash

  scalar    @array    slice:   @array[0, 2]  @hash{'a', 'b'}

  list      %hash     element: $array[0]     $hash{'a'}

            &sub

            *glob    SCALAR VALUES

                     number, string, reference, glob, undef

  REFERENCES

  \     references      $$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     =          =        perl.plover.com

  ->                      +          .        search.cpan.org

  ++ --                   == !=      eq ne         cpan.org

  **                      < > <= >=  lt gt le ge   pm.org

  ! ~ \ u+ u-             <=>        cmp           tpj.com

  =~ !~                                            perldoc.com

  * / % x                 SYNTAX

  + - .                   for    (LIST) { }, for (a;b;c) { }

  << >>                   while  ( ) { }, until ( ) { }

  named uops              if     ( ) { } elsif ( ) { } else { }

  < > <= >= lt gt le ge   unless ( ) { } elsif ( ) { } else { }

  == != <=> eq ne cmp     for equals foreach (ALWAYS)

  &

  | ^              REGEX METACHARS            REGEX MODIFIERS

  &&               ^     string begin         /i case insens.

  ||               $     str. end (before \n) /m line based ^$

  .. ...           +     one or more          /s . includes \n

  ?:               *     zero or more         /x ign. wh.space

  = += -= *= etc.  ?     zero or one          /g global

  , =>             {3,7} repeat in range

  list ops         ()    capture          REGEX CHARCLASSES

  not              (?:)  no capture       .  == [^\n]

  and              []    character class  \s == [\x20\f\t\r\n]

  or xor           |     alternation      \w == [A-Za-z0-9_]

                   \b    word boundary    \d == [0-9]

                   \z    string end       \S, \W and \D negate

  DO

  use strict;        DON'T            LINKS

  use warnings;      "$foo"           perl.com

  my $var;           $$variable_name  perlmonks.org

  open() or die $!;  `$userinput`     use.perl.org

  use Modules;       /$userinput/     perl.apache.org

                                      parrotcode.org

  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  just use                    @INC  include paths

  11 blksz  POSIX::      3..9 only      @_    subroutine args

  12 blcks  strftime!    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@cpan.org>, 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