Re: distinguish between null variable and unset variable

On Thu, Jan 22, 2009 at 12:21 AM, Paul M Foster <paulf@quillandmouse.com>wrote: > 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 > I've replaced all my techniques for testing POST and GET data by the filter extension. http://php.net/filter -- Alexandre Gomes Gaigalas alexandre@gaigalas.net http://Alexandre.Gaigalas.Net