keys HASH keys ARRAY keys EXPR Called in list context, returns a list consisting of all the keys of the named hash, or in Perl 5.12 or later only, the indices of an array. Perl releases prior to 5.12 will produce a syntax error if you try to use an array argument. In scalar context, returns the number of keys or indices. Hash entries are returned in an apparently random order. The actual random order is specific to a given hash; the exact same series of operations on two hashes may result in a

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NAME NOTE DESCRIPTIONMaking References Using References Circular References Symbolic references Not-so-symbolic references Pseudo-hashes: Using an array as a hash Function Templates WARNING Postfix Dereference SyntaxPostfix Reference Slicing Assigning to References SEE ALSO NAME perlref - Perl references and nested data structures NOTE This is complete documentation about all aspects of references. For a shorter, tutorial introduction to just the essential features, see perlreftut

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NAME SYNOPSIS DESCRIPTION --help and --version NAME getopt, getopts - Process single-character switches with switch clustering SYNOPSIS use Getopt::Std; getopts('oif:'); # -o & -i are boolean flags, -f takes an argument # Sets $opt_* as a side effect. getopts('oif:', \%opts); # options as above. Values in %opts getopt('oDI'); # -o, -D & -I take arg. # Sets $opt_* as a side effect. getopt('oDI', \%opts); # -o, -D & -I take arg. Values in

NAME SYNOPSIS DESCRIPTION FUNCTIONS METHODS EXAMPLES SEE ALSO COPYRIGHT AUTHORS NAME Digest::MD5 - Perl interface to the MD5 Algorithm SYNOPSIS # Functional style use Digest::MD5 qw(md5 md5_hex md5_base64); $digest = md5($data); $digest = md5_hex($data); $digest = md5_base64($data); # OO style use Digest::MD5; $ctx = Digest::MD5->new; $ctx->add($data); $ctx->addfile($file_handle); $digest = $ctx->digest; $digest = $ctx->hexdigest; $digest = $ctx->b64digest; DESCRIPTION

NAME DESCRIPTION COMMON PROBLEMSPerl environment problems Portability problems Problematic System Interfaces Security problems DEBUGGINGPoking at Perl Using a source-level debugger gdb macro support Dumping Perl Data Structures Using gdb to look at specific parts of a program Using gdb to look at what the parser/lexer are doing SOURCE CODE STATIC ANALYSISlint, splint Coverity cpd (cut-and-paste detector) gcc warnings Warnings of other C compilers MEMORY DEBUGGERSvalgrind AddressSanitizer

NAME VERSION SYNOPSIS DESCRIPTION METHODS NOTES SEE ALSO MAINTAINER LICENSE NAME Thread::Semaphore - Thread-safe semaphores VERSION This document describes Thread::Semaphore version 2.12 SYNOPSIS use Thread::Semaphore; my $s = Thread::Semaphore->new(); $s->down(); # Also known as the semaphore P operation. # The guarded section is here $s->up(); # Also known as the semaphore V operation. # Decrement the semaphore only if it would immediately succeed. if ($s->down_nb()) {

NAME DESCRIPTION A basic example Key naming Implementation details NAME perlpragma - how to write a user pragma DESCRIPTION A pragma is a module which influences some aspect of the compile time or run time behaviour of Perl, such as strict or warnings . With Perl 5.10 you are no longer limited to the built in pragmata; you can now create user pragmata that modify the behaviour of user functions within a lexical scope. A basic example For example, say you need to create a class implementing ov

NAME DESCRIPTIONAn Object is Simply a Data Structure A Class is Simply a Package A Method is Simply a Subroutine Method Invocation Inheritance Writing Constructors Attributes An Aside About Smarter and Safer Code Method Call Variations Invoking Class Methods bless, blessed, and ref The UNIVERSAL Class AUTOLOAD Destructors Non-Hash Objects Inside-Out objects Pseudo-hashes SEE ALSO NAME perlobj - Perl object reference DESCRIPTION This document provides a reference for Perl's obj