Just gotta love theory... Why aren't these two stmts doing the same thing?

[eluser]WanWizard[/eluser]
No, OR is a boolean operator.

So when PHP evaluates this line, it will convert both elements of the statement to boolean, if needed. Now, isset() already returns a boolean. '' is a string, and an empty string evaluates to FALSE (see this for an explanation).

Your statement therefore translates to:

Code:

$prefix = isset($config['_prefix']) OR FALSE;

which, given the fact that this is an OR, will ignore the FALSE all together, since it will be either 'TRUE OR FALSE' (equals TRUE), or 'FALSE OR FALSE' (equals FALSE).