After the little experiment with PHP type comparison operation, I tried to find out what sort of comparison test the PHP switch-case statement enforces. The following is the code:
$cmd = 0;
switch($cmd)
{
case 'test': echo 'Inside Test case'; break;
default : echo 'Inside default case'; break;
}
To my surprise, the output was ‘Inside Test case’. The switch-case statement performs loose comparison behind the scene! If the case constructs construct perform complicated operations such as database manipulation or file handling, a zero parameter to the switch will create unwanted side-effects. This can be avoided if a case for handling zero input is inserted as the first case of the switch.
case 0 : /*do nothing*/ break;
However, if the 0 parameter comes directly from user via HTTP GET or POST request, it is automatically converted to a string and will not compare equal to any other string except maybe the empty string. You don’t need to add the zero case there.
Glorified Geek 
btw it’s often better to start with the default: when nothing is switched, internally in PHP it’s a lot faster because of less loops, usually default is where you start and then select something in a case, exactly the other way around 🙂
Like:
switch($_GET[‘foo’]) {
default: $bar = $z; break;
case ‘x’: $bar = $y; break;
case ‘y’; $bar = $x; break;
}