php array_shift vs在关联数组中取消设置

Question

Hi what is the difference between array_shift and unset in associative array?

I understand how in a normal array, if you use array_shift, the key is still there and only the first value goes away but in associative array, I don't see any difference between array_shift and unset.

below is the code example:

    $a=array("a"=>"red","b"=>"green","c"=>"blue");
    $key=key($a);
    unset($a[$key]);
    print_r ($a);

    //result: Array ( [b] => green [c] => blue )

    $b=array("a"=>"red","b"=>"green","c"=>"blue");
    array_shift($b);
    print_r ($b);

    //result: Array ( [b] => green [c] => blue )

Answer 1

array_shift will return the head of your array (in this instance entry "a")

while unset will remove an element by its key, say unset($a['b']) will leave you with Array ( [a] => red [c] => blue )