my $bitflags = 0; #all off.
vec( $bitflags, 0, 1 ) = 1; # Set the first bit.
print "First bit is set\n" if( vec( $bitflags, 0, 1 ) );
vec( $bitflags, 1, 1 ) = 1; # Set the second bit.
print "Second bit is set\n" if( vec( $bitflags, 1, 1 ) );
vec( $bitflags, 0, 1 ) = 0; # UnSet the first bit.
print "First bit is set\n" if( vec( $bitflags, 0, 1 ) );
print "First bit is off\n" if( !vec( $bitflags, 0, 1 ) );
# and so on...