// split the phrase by any number of commas or space characters,
// which include " ", \r, \t, \n and \f
$keywords = preg_split("/[\s,]+/", "hypertext language, programming");

$str = 'string';
$chars = preg_split('//', $str, -1, PREG_SPLIT_NO_EMPTY);
print_r($chars);

$str = 'hypertext language programming';
$chars = preg_split('/ /', $str, -1, PREG_SPLIT_OFFSET_CAPTURE);
print_r($chars);

hasil:
Array
(
[0] => Array
(
[0] => hypertext
[1] => 0
)

[1] => Array
(
[0] => language
[1] => 10
)

[2] => Array
(
[0] => programming
[1] => 19
)

)

Function foreach()

foreach (array_expression as $value)
statement
foreach (array_expression as $key => $value)
statement

* foreach example 1: value only */

$a = array(1, 2, 3, 17);

foreach ($a as $v) {
echo "Current value of \$a: $v.\n";
}

/* foreach example 2: value (with key printed for illustration) */

$a = array(1, 2, 3, 17);

$i = 0; /* for illustrative purposes only */

foreach ($a as $v) {
echo "\$a[$i] => $v.\n";
$i++;
}

/* foreach example 3: key and value */

$a = array(
"one" => 1,
"two" => 2,
"three" => 3,
"seventeen" => 17
);

foreach ($a as $k => $v) {
echo "\$a[$k] => $v.\n";
}

/* foreach example 4: multi-dimensional arrays */
$a = array();
$a[0][0] = "a";
$a[0][1] = "b";
$a[1][0] = "y";
$a[1][1] = "z";

foreach ($a as $v1) {
foreach ($v1 as $v2) {
echo "$v2\n";
}
}

/* foreach example 5: dynamic arrays */

foreach (array(1, 2, 3, 4, 5) as $v) {
echo "$v\n";
}