1次元配列の特定の値要素を削除するPHPの操作方法

<?php
$tmp = &#39;324&#39;;
$arr = array(
&#39;0&#39; => &#39;321&#39;,
&#39;1&#39; => &#39;322&#39;,
&#39;2&#39; => &#39;323&#39;,
&#39;3&#39; => &#39;324&#39;,
&#39;4&#39; => &#39;325&#39;,
&#39;5&#39; => &#39;326&#39;,
);

foreach( $arr as $k=>$v) {
 if($tmp == $v) unset($arr[$k]);
}
print_r($arr);
?>

Array
(
 [0] => 321
 [1] => 322
 [2] => 323
 [4] => 325
 [5] => 326
)

foreach( $arr as $k=>$v) {
 if($tmp == $v) unset($arr[$k]);
}
$arr = array_values($arr);
print_r($arr);
?>

foreach( $arr as $k=>$v) {
 if($tmp == $v) unset($arr[$k]);
}
$arr = array_merge($arr);
print_r($arr);
?>

$key=array_search($tmp ,$arr);
array_splice($arr,$key,1);
var_dump($arr);

$arr = array_merge(array_diff($arr, array($tmp)));
var_dump($arr);

$arr = array_merge(array_diff($arr, $tmp));
var_dump($arr);