The revision, version, and subversion of the Perl interpreter, represented as a version object.
This variable first appeared in perl v5.6.0; earlier versions of perl will see an undefined value. Before perl v5.10.0
$^V was represented as a v-string rather than a version object.
$^V can be used to determine whether the Perl interpreter executing a script is in the right range of versions. For example:
warn "Hashes not randomized!\n" if !$^V or $^V lt v5.8.1
While version objects overload stringification, to portably convert
$^V into its string representation, use
"%vd" conversion, which works for both v-strings or version objects:
printf "version is v%vd\n", $^V; # Perl's version
See the documentation of
use VERSION and
require VERSION for a convenient way to fail if the running Perl interpreter is too old.
$] for a decimal representation of the Perl version.
The main advantage of
$] is that, for Perl v5.10.0 or later, it overloads operators, allowing easy comparison against other version representations (e.g. decimal, literal v-string, "v1.2.3", or objects). The disadvantage is that prior to v5.10.0, it was only a literal v-string, which can't be easily printed or compared.
Mnemonic: use ^V for a version object.