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This method can be used to manipulate the internal order of the IxHash
elements by supplying a list of keys in the desired order.  Note however,
that any IxHash elements whose keys are not in the list will be removed from
the IxHash.

=item Length

Returns the number of IxHash elements.

=item SortByKey

Reorders the IxHash elements by textual comparison of the keys.

=item SortByValue

Reorders the IxHash elements by textual comparison of the values.

=back


=head1 EXAMPLE

    use Tie::IxHash;

    # simple interface
    $t = tie(%myhash, Tie::IxHash, 'a' => 1, 'b' => 2);
    %myhash = (first => 1, second => 2, third => 3);
    $myhash{fourth} = 4;
    @keys = keys %myhash;
    @values = values %myhash;
    print("y") if exists $myhash{third};
    
    # OO interface
    $t = Tie::IxHash->new(first => 1, second => 2, third => 3);
    $t->Push(fourth => 4); # same as $myhash{'fourth'} = 4;
    ($k, $v) = $t->Pop;    # $k is 'fourth', $v is 4
    $t->Unshift(neg => -1, zeroth => 0); 
    ($k, $v) = $t->Shift;  # $k is 'neg', $v is -1
    @oneandtwo = $t->Splice(1, 2, foo => 100, bar => 101);
    
    @keys = $t->Keys;
    @values = $t->Values;
    @indices = $t->Indices('foo', 'zeroth');
    @itemkeys = $t->Keys(@indices);
    @itemvals = $t->Values(@indices);
    $t->Replace(2, 0.3, 'other');
    $t->Delete('second', 'zeroth');
    $len = $t->Length;     # number of key-value pairs

    $t->Reorder(reverse @keys);
    $t->SortByKey;
    $t->SortByValue;


=head1 BUGS

You cannot specify a negative length to C<Splice>. Negative indexes are OK,
though.

Indexing always begins at 0 (despite the current C<$[> setting) for 
all the functions.


=head1 TODO

Addition of elements with keys that already exist to the end of the IxHash
must be controlled by a switch.

Provide C<TIEARRAY> interface when it stabilizes in Perl.

Rewrite using XSUBs for efficiency.


=head1 AUTHOR

Gurusamy Sarathy        gsar@umich.edu

Copyright (c) 1995 Gurusamy Sarathy. All rights reserved.
This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.


=head1 VERSION

Version 1.21    20 Nov 1997


=head1 SEE ALSO

perl(1)

=cut