Delete element from array if not found - php

Question

I have some code I created which is supposed to see if something exists in an array of strings. If it does not exist, I want to delete that element of the array. I thought we do this with unset, but it doesnt seem to be working. Mind helping?
echo '<br>size of $games before end-check: '.sizeof($games);
foreach ($games as $game) {
$game_end_marker = "body = (game)#";
$game_end_pos = strpos($game, $game_end_marker);
if ($game_end_pos !== false) {
echo "<br>end of game found";
}
else {
echo "<br>end of game not found. incomplete game";
unset($game);
}
}
echo '<br>size of $games after end-check: '.sizeof($games);
output:
size of $games before end-check: 2
end of game found
end of game not found. incomplete game
size of $games after end-check: 2

Answer 1

Because you unset the variable $game, not the element in the array. Try this:
echo '<br>size of $games before end-check: '.sizeof($games);
foreach ($games as $index => $game) {
$game_end_marker = "body = (game)#";
$game_end_pos = strpos($game, $game_end_marker);
if ($game_end_pos !== false) {
echo "<br>end of game found";
}
else {
echo "<br>end of game not found. incomplete game";
unset($games[$index]);
}
}
echo '<br>size of $games after end-check: '.sizeof($games);

Answer 2

You have to unset the index of game.
foreach ($games as $key => $value) {
// all your logic here, performed on $value
unset($games[$key]);
}

Answer 3

This merely unsets your local reference to the element. You need to be referring directly to the array.
foreach($games as $key => $game)
unset($games[$key]);

Answer 4

That won't work: foreach creates a new variable, copying the old one. Unsetting it will do nothing to the original value. Likewise, making it a reference won't work either, since only the reference would be deleted.
The nicest way to do this would be with array_filter:
$games = array_filter($games, function($game) {
$game_end_marker = "body = (game)#";
$game_end_pos = strpos($game, $game_end_marker);
if ($game_end_pos !== false) {
echo "<br>end of game found";
return true;
}
else {
echo "<br>end of game not found. incomplete game";
return false;
}
});
This uses the anonymous function syntax introduced in PHP 5.3. If the function returns true, the element is kept; if it returns false, the element is removed.

Answer 5

You can also call by reference:
foreach($games as &$game) {
unset($game);
}
In this way you can also change $game (eg. $game .= " blah";) and the original array will be modified.

Answer 6

You can use array_splice in conjunction with an incrementally-increasing index variable to remove the current item from the array:
$index = 0;
foreach ($games as $game) {
$game_end_marker = "body = (game)#";
$game_end_pos = strpos($game, $game_end_marker);
if ($game_end_pos !== false) {
echo "<br>end of game found";
}
else {
echo "<br>end of game not found. incomplete game";
array_splice($games, $index, 1);
}
$index++;
}