foreach
-----
<?php

foreach ($arr as $val) {

}

foreach ($arr as &$val) {

}

foreach ($arr as $key => $val) {

}

foreach ($arr as $key => &$val) {

}
-----
foreach ($arr as $val) {
}
foreach ($arr as &$val) {
}
foreach ($arr as $key => $val) {
}
foreach ($arr as $key => &$val) {
}