Lewey Jimoya Lewey Jimoya - 22 days ago 6
PHP Question

How to check if result from array_intersect is empty?

I am trying to check the result of an array_intersect as a regular array but it always returns true even if the array is empty.

$lecturedayssplit1 = preg_split("/(?=[A-Z])/", "TF");
$lecturedayssplit2 = preg_split("/(?=[A-Z])/", "MTh");
$lectolec=array_intersect($lecturedayssplit1,$lecturedayssplit2);
if (count($lectolec) > 0) {
echo "Yeah!!!";
print_r($lectolec);
} else {
echo "Nooo!";
print_r($lectolec);
}


$lectolec
in the problem shouldn't return a count greater than 0 because there is no intersection between the two arrays. I also tried
if (empty($lectolec))
but it also didn't work. Hopefully someone can help out. Thanks in advance!

Answer

Because you are using a "zero-width positive lookahead" (?=[A-Z]) regex, it is matching an empty sequence in the beginning of each test. Therefore, array_intersect matches that empty sequence in both.

You can use the flag PREG_SPLIT_NO_EMPTY to ignore those empty results.

$lecturedayssplit1 = preg_split("/(?=[A-Z])/", "TF", -1, PREG_SPLIT_NO_EMPTY);
$lecturedayssplit2 = preg_split("/(?=[A-Z])/", "MTh", -1, PREG_SPLIT_NO_EMPTY);
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