Question

isset() in php 5.3 seems to be behaving unexpectedly. I have a class called DB details that encapsulates a bunch of string properties with getters and setters.

$dbdetails->getDatabasename() evaluates to a string (“mydb”)

This throws a 500 error:

if(!isset($dbdetails->getDatabasename())){
//do something
}

This works fine

$databasename = $dbdetails->getDatabasename();
if(!isset($databasename)){
//do something
}

I wasn’t able to see any log output because apache sent back a 500 even though the error ini param is set (sic) to On. I know this is something to do with the isset call for sure.
Any idea what could be wrong, or did I find a PHP bug?

Answer 1

The isset function checks whether a variable is set. Checking against $databasename is valid, because it is a variable that can be set or not. Checking against a function is invalid, because it simply isn’t a variable.

You probably want to use is_null( $value ) when checking the immediate result of a function.

---

An example from the comments on the the is_null documentation:

<?php
function test( ) { return null; }
var_dump( is_null( test( ) ) ); // displays "true"
var_dump( isset( test( ) ) ); // parse error, because "test()" is not a variable
?>

• PHP: is_null
• PHP: isset