例子会显示你的区别

  $ array = array（1，2）; 
 foreach（$ array为$ value）{
 $ value ++; 
} 
 print_r（$ array）; // 1，2，因为我们迭代了
 $ b foreach（$ array as& $ value）{
 $ value ++; 
} 
 print_r（$ array）; // 2,3，因为我们迭代了对数组
 

的实际值的引用。查看PHP文档这里： http://pl.php.net/manual/en/ control-structures.foreach.php

Possible Duplicate:
Reference - What does this symbol mean in PHP?

I need to know why we use ampersand before the variable in foreach loop

foreach ($wishdets as $wishes => &$wishesarray) {
    foreach ($wishesarray as $categories => &$categoriesarray) {

    }
}

Thanks

This example will show you the difference

$array = array(1, 2);
foreach ($array as $value) {
    $value++;
}
print_r($array); // 1, 2 because we iterated over copy of value

foreach ($array as &$value) {
    $value++;
}
print_r($array); // 2, 3 because we iterated over references to actual values of array

Check out the PHP docs for this here: http://pl.php.net/manual/en/control-structures.foreach.php