perlcheat - Perl 5 Cheat Sheet
This 'cheat sheet' is a handy reference, meant for beginning Perl programmers. Not everything is mentioned, but 195 features may already be overwhelming.
- 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 /o cmpl pat. once
- list ops () capture
- not (?:) no capture REGEX CHARCLASSES
- and [] character class . == [^\n]
- or xor | alternation \s == whitespace
- \b word boundary \w == word characters
- \z string end \d == digits
- DO \S, \W and \D negate
- use strict; DON'T
- use warnings; "$foo" LINKS
- my $var; $$variable_name perl.com
- open() or die $!; `$userinput` use.perl.org
- use Modules; /$userinput/ perl.apache.org
- FUNCTION RETURN LISTS
- stat localtime caller SPECIAL VARIABLES
- 0 dev 0 second 0 package $_ default variable
- 1 ino 1 minute 1 filename $0 program name
- 2 mode 2 hour 2 line $/ input separator
- 3 nlink 3 day 3 subroutine $\ output separator
- 4 uid 4 month-1 4 hasargs $| autoflush
- 5 gid 5 year-1900 5 wantarray $! sys/libcall error
- 6 rdev 6 weekday 6 evaltext $@ eval error
- 7 size 7 yearday 7 is_require $$ 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
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.
Juerd Waalboer <#####@juerd.nl>, with the help of many Perl Monks.
- 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