Yes you can do a binary search. Yet is will find the correct placement faster for large lists. In fact I have a module on cpan called File::SortedSeek that implements binary searches in large files so I appreciate the algorithm :-) However in this scenario having found the index you then have a practical problem. It is not possible to insert a value into the middle of an array, which is really just a contiguous sequence of SV* What you have to do is make space for it. Splice does that by moving a large chunk (or the entire array). The bubble algorithm also does it and is (in past testing) about twice as fast as just calling sort. Here is a binary search implementation. Benchmarking the options is left to you. 

my @ary = (1..4, 6..10);

for my $val( 0, 5, 11, 0, 5, 11 ) {
    binary( \@ary, $val );
    print "@ary\n";
}

sub binary {
    my ( $ary, $val ) = @_;
    my ( $min, $max, $last, $i ) = ( 0, scalar @{$ary}, 0, 0 );
    while ( 1 ) {
        $i = int( ($min+$max)/2 );
        # print "i=$i\n";  
      last if $last == $i;
        $last = $i;
        if ( $ary->[$i] < $val ) {
            $min = $i;
        }
        elsif ( $ary->[$i] > $val ) {
            $max = $i;
        }
        else {
            # values are equal so we have a valid index
            last;
        }
    } 
    $i++ if $i;   # for index 0 we want that, otherwise we want next p
+osition   
    splice @$ary, $i, 0, $val;
}

__DATA__
0 1 2 3 4 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10 11
0 0 1 2 3 4 5 6 7 8 9 10 11
0 0 1 2 3 4 5 5 6 7 8 9 10 11
0 0 1 2 3 4 5 5 6 7 8 9 10 11 11

[download]

cheers

tachyon

In reply to Re^3: Insert Into a Sorted Array by tachyon
in thread Insert Into a Sorted Array by ketema

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