Variable reference, unexpected output

[nebulom]

I've got this code and I expect to output 5 and 5 as the result but outputs 4 and 5. Please explain a bit, quite confused.

<?php

    function &find_var($one, $two, $three) {

        if(($one > 0) && ($one <= 10)) return $one;
        if(($two > 0) && ($two <= 10)) return $two;
        if(($three > 0) && ($three <= 10)) return $three;

    }

    $c_one = 'foo';
    $c_two = 42;
    $c_three = 4;

    $right_var = &find_var($c_one, $c_two, $c_three);

    $right_var++;

    echo "The value of \$c_three and \$right_var are: ";
    echo "$c_three and $right_var<BR>\n";

?>

Thanks in advance.