迭代和修改数组最佳方法

Question

The following is the best way to iterate through and modify array in PHP5.*+

^{(source: http://zend-php.appspot.com/questions_list -- question #3)}

$array = array("one" => 1, "two" => 2, "three" => 3, "four" => 4, "five" => 5);
foreach($array as $key => &$val) {
   $val += 1;
}

What is it about this method of iterating and modifying that makes it better than others?

Can someone please explain how come this actually works?

This iterates just fine, why include as $key => &$val if we are not using the keys?, also why do we need to include the & in &$val:

foreach($array as $val){
   echo $val;
}

I appreciate the explanation, Thanks in advance!

Answer 1

Since they intend to modify the value, getting it as a reference is clever.

$array = array("one" => 1, "two" => 2, "three" => 3, "four" => 4, "five" => 5);
foreach($array as $key => &$val) {
   $val += 1;
}

Will add 1 to all values.

If you did:

foreach($array as $key => $val) {
   $val += 1;
}

Nothing would happen.

I strongly disagree that it is the best way though. I much prefer to see:

foreach($array as $key => $val) {
   $array[$key] += 1;
}

because it's much more straightforward. I'll gladly believe it doesn't perform as well, but I also don't care (unless there is a reason to start optimizing).

It's also worth mentioning that using references can lead to strange situations, such as: PHP reference causes data corruption

PS. I didn't downvote. I'm getting really annoyed by people downvoting and not leaving a comment.