Re: distinguish between null variable and unset variable

On Wed, Jan 21, 2009 at 05:27:35PM -0800, Jack Bates wrote: > How can I tell the difference between a variable whose value is null and > a variable which is not set? > > // cannot use === null: > > ket% php -r '$null = null; var_dump(null === $null);' > bool(true) > ket% php -r 'var_dump(null === $unset);' > bool(true) > ket% > > // - cannot use isset() either: > > ket% php -r '$null = null; var_dump(isset($null));' > bool(false) > ket% php -r 'var_dump(isset($unset));' > bool(false) > ket% Oh I *love* this problem. I still haven't found the perfect solution for it. But since a lot of things in PHP float around as strings, I often use strlen(trim($var)) == 0 to determine the "emptiness" of a variable. But it all depends on what type of variable you expect to receive. I don't have this problem so much with methods and functions, since I specifically engineer them to give me exact results. But I get it when testing POST and GET variables from web pages. Paul -- Paul M. Foster