通过嵌套的foreaches在多维数组中取消设置键

Question

Seems strange I can't find an answer to this, but here goes:

This:

foreach ($stuffs as $stuffRow) {
    foreach ($stuffRow as $stuff) {
        if($stuff=== null){
            unset($stuff);
        }
    }
}

is not working.

I know I shouldn't say "isn't working", but that's all I've got. The if condition works; I've tested it. However, when I apply unset, the key=>value is still there.

Note: PHP 5.3

Many thanks in advance!

Answer 1

While this might work (i never do it this way and not tested it):

foreach ($stuffs as &$stuffRow) {
    foreach ($stuffRow as &$stuff) {
        if($stuff=== null){
            unset($stuff);
        }
    }
}

If i remember correctly, passing by reference isn't a good idea in foreachs (but can't remember why, might have been in the php doc somewhere, maybe someone can clarify in the comments, but i think it's because foreach works on a copy of the array and passing a reference passes the reference to the copy, not the original, though that is just an educated guess). Instead, try this.

foreach ($stuffs as $key1=>$stuffRow) {
    foreach ($stuffRow as $key2=>$stuff) {
        if($stuff=== null){
            unset($stuffs[$key1][key2]);
        }
    }
}

The reason your code didn't work by the way is because foreach loops iterate over a COPY of your array.