=over

=item oct EXPR

=item oct

Interprets EXPR as an octal string and returns the corresponding
value.  (If EXPR happens to start off with C<0x>, interprets it as
a hex string instead.)  The following will handle decimal, octal, and
hex in the standard Perl or C notation:

    $val = oct($val) if $val =~ /^0/;

If EXPR is omitted, uses C<$_>.  This function is commonly used when
a string such as C<644> needs to be converted into a file mode, for
example. (Although perl will automatically convert strings into
numbers as needed, this automatic conversion assumes base 10.)

=back