What is the difference betweeen %INC and @INC?

Question

What is the difference between %INC and @INC in Perl?

Answer 1

The @INC array holds all the file system paths where Perl will be looking for modules when you use or require them.

After use or require, the %INC hash will contain the loaded modules and where they were loaded from.

Examples from my laptop:

@INC:

'/etc/perl',
'/usr/local/lib/perl/5.10.0',
'/usr/local/share/perl/5.10.0',
'/usr/lib/perl5',
'/usr/share/perl5',
'/usr/lib/perl/5.10',
'/usr/share/perl/5.10',
'/usr/local/lib/site_perl',
'.'

and %INC:

'warnings/register.pm' => '/usr/share/perl/5.10/warnings/register.pm',
'bytes.pm' => '/usr/share/perl/5.10/bytes.pm',
'XSLoader.pm' => '/usr/lib/perl/5.10/XSLoader.pm',
'Carp.pm' => '/usr/share/perl/5.10/Carp.pm',
'Exporter.pm' => '/usr/share/perl/5.10/Exporter.pm',
'warnings.pm' => '/usr/share/perl/5.10/warnings.pm',
'overload.pm' => '/usr/share/perl/5.10/overload.pm',
'Data/Dumper.pm' => '/usr/lib/perl/5.10/Data/Dumper.pm'

(%INC contains Data::Dumper because I used it to quickly dump those two values).

Answer 2

See perldoc perlvar for @INC, %INC and all other special variables in Perl.

Answer 3

http://perl.apache.org/docs/general/perl_reference/perl_reference.html#The__INC_array