文字列⇔配列の変換

$arr = array("あ","い","う");
$str = implode(",", $arr);
print($str);

$str =  "'" .implode("','", $arr)."'"; 
print($str);

$str = 'apple orange pear banana';
$arr = explode(" ", $str); // 半角スペースで分割
print_r($arr);

$str = 'apple orange pear banana';
$arr = preg_split("/\s/", $str);
print_r($arr);

$str = 'apple,orange pear
banana;remon';

$arr = preg_split("/[,:;\n\s]/", $str);
print_r($arr);