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
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 ignore 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
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.