Unset an array element inside a foreach loop [duplicate]

Answer 1

You're unsetting the reference (breaking the reference). You'd need to unset based on a key:

foreach ($this->result['list'] as $key => &$row) {
    if ($this_row_is_boring) {
        unset($this->result['list'][$key]);
    }
}

Answer 2

A bit of an explanation to the answers above.

After unset($row) the variable $row is unset. That does not mean the data in $row is removed; the list also has an element pointing to $row.

It helps to think of variables as labels. A piece of data can have one or more labels, and unset removes that label but does not touch the actual data. If all labels are removed the data is automatically deleted.

Answer 3

foreach ($this->result['list'] as $key => &$row) {
    if ($this_row_is_boring) {
        unset($this->result['list'][$key]);
    }
}
unset($row);

Remember: if you are using a foreach with a reference, you should use unset to dereference so that foreach doesn't copy the next one on top of it. More info