What is the PHP syntax to check "is not null" or an empty string? [duplicate]

Question

Possible Duplicate:
Check if a variable is empty

Simple PHP question:

I have this stement:

if (isset($_POST["password"]) && ($_POST["password"]=="$password")) { ...//IF PASSWORD IS CORRECT STUFF WILL HAPPEN HERE } 

Somewhere above this statement I use the following line in my JavaScript to set the username as a variable both in my JavaScript and in my PHP:

uservariable = <?php $user = $_POST['user']; print ("\"" . $user . "\"")?>; 

What I want to do is add a condition to make sure $user is not null or an empty string (it doesn't have to be any particular value, I just don't want it to be empty. What is the proper way to do this?

I know this is a sill question but I have no experience with PHP. Please advise, Thank you!

Answer 1

Null OR an empty string?

if (!empty($user)) {} 

Use empty().

---

After realizing that $user ~= $_POST['user'] (thanks matt):

var uservariable='<?php      echo ((array_key_exists('user',$_POST)) || (!empty($_POST['user']))) ? $_POST['user'] : 'Empty Username Input'; ?>'; 

Answer 2

Use empty(). It checks for both empty strings and null.

if (!empty($_POST['user'])) {   // do stuff } 

From the manual:

The following things are considered to be empty:

"" (an empty string)   0 (0 as an integer)   0.0 (0 as a float)   "0" (0 as a string)     NULL   FALSE   array() (an empty array)   var $var; (a variable declared, but without a value in a class)