Difference between !empty($var) & !$var ??

[darthmahon]

Hey,

Just wanted to know what is the difference between the following:

if (!empty($var)) { do }

if  (!$var) { do }

I thought the bottom checked to see if something was empty?

Cheers,
Chris

[LordShryku]

The bottom will throw a notice of "undefined variable" if it's not set.

[darthmahon]

Oh right. I only ask because I have a form that allows users to upload a file.

Now if I use the top, and they have not selected a file it stops and says "Upload a file please". The second option however, does nothing, even if no file has been selected.

So I'm not sure what's going on there.

[drew010]

you should use empty for what you are trying to do.

empty will check for an existing variable and see if its contents are a null string and !$var will test to see if the variable exists or not (or if its boolean if its true or false). since its from a form, it will always be created, however, wheter or not its empty depends on the user choosing a file or not.

$var = "";
echo empty($var); //1 (true)
echo !$var; //1 (true) because its empty, aka bool false and ! takes the opposite.