Only Variables can be passed by reference error

Question

An error occurred in script \'/usr/local/apache2/htdocs/read.php\' on line 197: Only variables should be passed by reference (line 196 is $ext = strtolo

Answer 1

You need to make the result of explode() a variable before you pass it on

$var = explode('.',$filename);
$ext = strtolower(array_pop($var));

Answer 2

That code is passing the result of the explode function (a value) into array_pop, but array_pop expects an array variable (by reference), not a value. (The & in the array_pop declaration tells us that it's expecting to accept a reference.)

You can fix it by using an array variable to store the result of explode, and then passing that into array_pop.