try this short & sweet code -
$array = array (1,4,2,1,7,4,9,7,5,9);
$unique = array();
foreach($array as $v){
isset($k[$v]) || ($k[$v]=1) && $unique[] = $v;
}
var_dump($unique);
Output -
array(6) {
[0]=>
int(1)
[1]=>
int(4)
[2]=>
int(2)
[3]=>
int(7)
[4]=>
int(9)
[5]=>
int(5)
}