The outcomes of testing things using just if() is.

php_if_statements.php

<?php
/**
 * As I never am quite sure the outcome of testing variables and arrays using
 * just the plain if(), I thought I'd make a quick test so that I can refer to
 * it when I next forget this!
 * 
 * Manual ref: http://uk3.php.net/manual/en/language.types.boolean.php#language.types.boolean.casting
 */
$emptyArray = array(); // False
$filledArray = array('One','Two'); // True
$boolTrue = true; // True
$boolFalse = false; // False
$boolNull = null; // False
$emptyString = ''; // False
$filledString = 'A string'; // True

if ($emptyArray) {
	var_dump('If thinks emptyArray is true');
}
if ($filledArray) {
	var_dump('If thinks filledArray is true');
}
if ($boolTrue) {
	var_dump('If thinks boolTrue is true');
}
if ($boolFalse) {
	var_dump('If thinks boolFalse is true');
}
if ($boolNull) {
	var_dump('If thinks boolNull is true');
}
if ($emptyString) {
	var_dump('If thinks emptyString is true');
}
if ($filledString) {
	var_dump('If thinks filledString is true');
}