php中数组中&的问题

1.代码：

<?php
$arr = array('one','two','three'); 

foreach ($arr as $value){
    echo 'Value:'.$value.'<br />';
}
echo '<hr/>';

foreach ($arr as &$value){
 echo 'Value:'.$value.'<br />';
}
echo '<hr/>';
// reset($arr);

foreach ($arr as $value){
    echo 'Value:'.$value.'<br />';
} 

?>

2.结果

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3.原因：

第一次带&的foreach并没有改变数组的内容。。
而是最后一次循环$value引用了数组的最后一个项 (可以测试一下，在第一次循环结束后unset($value)，第二次循环的结果就不会有变化)，
在你第二个foreach也是使用的$value变量，这才造成了怪异的问题(可以换个变量,比如$val，输出的数组就不会有变化)。
第二个foreach是赋值给$value，但是这时的$value是引用的数组的最后一个值，
所以
第一次循环把one赋值给了最后一个值，
第二次把two赋值给最后一个，
第三次也就是最后一个已经在第二次循环被赋值为two，所以仍然是two。