Looking at someone else's PHP code is a little confused

foreach ($data as &$e) {}和foreach ($data as $e) {}有什么区别？

Reply content:

foreach ($data as &$e) {}和foreach ($data as $e) {}有什么区别？

$data = [1,2,3];foreach($data as &$e){    $e+=1;}var_dump($data);//[2,3,4]unset($e);$data = [1,2,3];foreach($data as $e){    $e+=1;}var_dump($data);//[1,2,3]

The upstairs is clear and gives two more links:

http://php.net/manual/en/control-structures.foreach.php

http://php.net/manual/en/language.references.php

One is a reference, which is used for the original value itself; one is used and the original value is not changed.

Do not add &, it is equivalent to the internal copy of a variable to use, will not modify the original value, the address will not change.

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