These days, the way to develop is to have E_ALL and maybe even throw in E_STRICT if you are really hard core. That of course means having all your variables initialized before they are used. You could just do something like this:
<php



$var1 = 0;

$var2 = "";

$var3 = 0.00;

$var4 = array();

$var5 = new stdClass;



?>

That works fine and is pretty clear. However, I think a more elegant solution is to use settype() like this:
<php



settype($var1, "int");

settype($var2, "string");

settype($var3, "float");

settype($var4, "array");

settype($var5, "object");



?>

IMHO, this is much more clear. Its a standard way to set the type and default value of your variables. You see, settype() assigns a default value to the variables if they do not exist already.

Another handy use is in a function.
<?php



function myfunc( $someint, $somestring) {



settype($someint, "int");

    settype($somestring, "string");



if($someint>0){

        echo $somestring;

    }

}



?>

Now this example does not do much for the string, but it ensures the int variable is an integer. Without the settype() line, the if() statement would evaluate to true if some string value was passed in for $someint.

The one down side that some may not like is with arrays and objects. If the variable is a scalar type (int, string, float, boolean), it will be changed into an array/object with a member called scalar that contains the scalar value.

There is no note in the official docs (there is one in the comments) about settype initializing a variable. I think I will submit a documentation update request in the bug system. I am also considering writing a test to ensure this unknown, but IMHO very useful feature stays in PHP.