[php] Only variables should be passed by reference

// Other variables
$MAX_FILENAME_LENGTH = 260;
$file_name = $_FILES[$upload_name]['name'];
//echo "testing-".$file_name."<br>";
//$file_name = strtolower($file_name);
$file_extension = end(explode('.', $file_name)); //ERROR ON THIS LINE
$uploadErrors = array(
    0=>'There is no error, the file uploaded with success',
    1=>'The uploaded file exceeds the upload max filesize allowed.',
    2=>'The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form',
    3=>'The uploaded file was only partially uploaded',
    4=>'No file was uploaded',
    6=>'Missing a temporary folder'
);

Any ideas? After 2 days still stuck.

PHP offical Manual : end()

Parameters

array

The array. This array is passed by reference because it is modified by the function. This means you must pass it a real variable and not a function returning an array because only actual variables may be passed by reference.

First, you will have to store the value in a variable like this

$value = explode("/", $string);

Then you can use the end function to get the last index from an array like this

echo end($value);

I hope it will work for you.

end(...[explode('.', $file_name)]) has worked since PHP 5.6. This is documented in the RFC although not in PHP docs themselves.

Just as you can't index the array immediately, you can't call end on it either. Assign it to a variable first, then call end.

$basenameAndExtension = explode('.', $file_name);
$ext = end($basenameAndExtension);

Php 7 compatible proper usage:

$fileName      = 'long.file.name.jpg';
$tmp           = explode('.', $fileName);
$fileExtension = end($tmp);

echo $fileExtension;
// jpg

Try this:

$parts = explode('.', $file_name);
$file_extension = end($parts);

The reason is that the argument for end is passed by reference, since end modifies the array by advancing its internal pointer to the final element. If you're not passing a variable in, there's nothing for a reference to point to.

See end in the PHP manual for more info.

Since it raise a flag for over 10 years, but works just fine and return the expected value, a little stfu operator is the goodiest bad practice you are all looking for:

$file_extension = @end(explode('.', $file_name));

But warning, don't use in loops due to a performance hit. Newest version of php 7.3+ offer the method array_key_last() and array_key_first().

https://www.php.net/manual/en/function.array-key-last.php

save the array from explode() to a variable, and then call end() on this variable:

$tmp = explode('.', $file_name);
$file_extension = end($tmp);

btw: I use this code to get the file extension:

$ext = substr( strrchr($file_name, '.'), 1);

where strrchr extracts the string after the last . and substr cuts off the .

PHP complains because end() expects a reference to something that it wants to change (which can be a variable only). You however pass the result of explode() directly to end() without saving it to a variable first. At the moment when explode() returns your value, it exists only in memory and no variable points to it. You cannot create a reference to something (or to something unknown in the memory), that does not exists.

Or in other words: PHP does not know, if the value you give him is the direct value or just a pointer to the value (a pointer is also a variable (integer), which stores the offset of the memory, where the actual value resides). So PHP expects here a pointer (reference) always.

But since this is still just a notice (not even deprecated) in PHP 7, you can savely ignore notices and use the ignore-operator instead of completely deactivating error reporting for notices:

$file_extension = @end(explode('.', $file_name));

$file_extension = end(explode('.', $file_name)); //ERROR ON THIS LINE

change this line as,

$file_extension = end((explode('.', $file_name))); //no errors

Technique is simple please put one more brackets for explode,

(explode()), then only it can perform independently..

Everyone else has already given you the reason you're getting an error, but here's the best way to do what you want to do: $file_extension = pathinfo($file_name, PATHINFO_EXTENSION);