Fixing 'Can't use function return value in write context' in PHP Posted on March 5, 2014

You might have encountered this error in one of your PHP scripts. Although the reason for this problem is a testament to how completely messed PHP is, it is quite simple.

Let’s take a look at this function for example:

if(empty(trim($var))){ //Can't use function return value in write context
 ...

The reason is that empty() is not a function but a language construct, and will only work on variables, not function return values.

This would work just fine:

$var = trim($var);
if(empty($var)){ //All good
 ...

That’s PHP for you.