Deleting an array element with PHP

Question

I have an array with several elements. The array keys are numeric.

I now want to remove a certain element. All I know is the element's content, not the key.

Is there an easy way to remove this element from the array? Or do I need to loop through all elements of the array to get the key and then unset the element with that key?

• Your Common Sense: for the several elements it doesn't really matter.

Answer 1

You can use array_filter to remove all elements with that particular value:

$arr = array_filter($arr, function($val) { return $val !== 'some value'; });

This example uses an anonymous function that were introduced with PHP 5.3. But you can use any other callback function.

Or you can use array_keys to get the keys of all elements with that value and do a diff on the keys after:

$arr = array_diff_key($arr, array_flip(array_keys($arr, 'some value', true)));

• nico: +1: didn't know the array_filter function, seems to be really handy.
• Your Common Sense: @nico array_filter seems overkill if you have unique elements in your array. it will loop through all elements. And array_flip will spoil your data if there are non-unique elements. Both solutions are funny, but impractical. Being not an actor, but a programmer, always make your code as easy and readable as possible. You'll lave to read it in the future. So, your own one is way better.
• Gumbo: @Col. Shrapnel: The complexity of both array_search and array_filter is O(n). And array_flip is only applied of an array of keys; so there won’t be any information loss.
• Starx: @Gumbo, Dont worry, here is another +1, for a great answer.
• Gumbo: @Col. Shrapnel: Yes, the average behavior is O(n/2) for array_search versus Θ(n) for array_filter; but it’s still O(n) in both cases.

Answer 2

You can use the array search function to get the key

$key = array_search('searchterm', $items); 
unset($items[$key]);

• nico: Just be sure to check the return value for array_search (see my answer below)

Answer 3

sure

foreach($myarray as $key=>$item) {
 if($item=='myknowncontent') { unset($myarray[$key]; }
}

• user478419: Well, yes, that's what I mentioned. I was just wondering if I could unset the element without looping through all elements of the array.
• Starx: As Col. Shrapnel said for the several elements it doesn't really matter
• Starx: @Starx. Wow you got me, I am not a Native English Speaker. Then... What..(Your Point)
• nico: Nothing, just did not understand the meaning of the sentence you quoted, that's all! :)
• Your Common Sense: @nico you have to loop through all elements only if they aren't unique. otherwise you can use break operator.

Answer 4

You can use array_search to find the corresponding key:

$key = array_search("whatever", $array);
if ($key !== FALSE)
 unset($array[$key]);

• Gumbo: This will remove $array[0] if there is no element with such value.