brackets []

Quick question... I am hoping some could explain this to me. I have an array like this: $completed = array($value1, $value2, $value3); where the values are sent via a form. <input type="checkbox" name="completed[]" value="value1"> when I do print_ r() to see what's in the array I get this: Array ( [0] => [1] => [2] => ) An empty array. But when I do this: $completed[] = array($value1, $value2, $value3); Array ( [0] => 1 [1] => 1 [2] => Done [3] => 2 [4] => 1 [5] => 3 [6] => 1 [7] => 4 [8] => 1 [9] => Array ( [0] => [1] => [2] => ) ) I get a multidimensional array with keys and values. How can I get this array to be one dimensional? Much Thanks - CH