When is NULL not NULL?

ajwws

I've tried creating a link like

but when I subsequently check the value of view_cat using if(view_cat == NULL), the test fails.

Any pointers on what I'm doing wrong and the correct way to do this?

Thanks,

A.J.Wilson

kparker

Either

should do the trick. (What's going on here is that all http arguments are passed as strings, so putting NULL inside the quoted string forming the url just puts that characters N U L L in there. The token NULL only has special meaning as PHP program text.)

[deleted]

In reverse, you could also change from
if ($var = NULL)
to
if ($var = 'NULL')

himura_drew

try this:

then:

if (isset($view_cat)) {
    <i>your code block</i>
}

i tried doing this without the <b>isset()</b> function before... but when i tried to use the same code in a different server environment, it reports an error when trying to operate on an undefined variable.

ajwws

Thanks for all the comments. I didn't think about the NULL being in a string.

Something like

$trail = "<A HREF=\"$PHP_SELF?view_cat=\">Top</A>";

works, but it just didn't feel right to leave the view_cat= hanging with nothing after the equal sign 🙂 I finally decided to break up the string, like

$trail = "<A HREF=\"$PHP_SELF?view_cat=".NULL."\">Top</A>";

A.J. Wilson