perlcheat



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




NAME

       perlcheat - Perl 5 Cheat Sheet


DESCRIPTION

       This ’cheat sheet’ is a handy reference, meant for beginning Perl pro-
       grammers. 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 sev-
       eral 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



perl v5.8.6                       2004-11-05                      PERLCHEAT(1)

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